Can't build my project after converting it to c++

Hi, I am using UE4.18.3, and I wanted to use the VR expansion plugin. I followed the instructions to the best of my ability, but when I go to build the project, I get what appears to be a bunch of syntax errors? I am using visual studio 2017. It spits out the following

   1>------ Build started: Project: UE4, Configuration: BuiltWithUnrealBuildTool Win32 ------
    2>------ Build started: Project: Chasing_White_Rabbit, Configuration: Development_Editor x64 ------
    2>Performing 5 actions (4 in parallel)
    2>SharedPCH.Engine.cpp
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(2): error C4138: '*/' found outside of comment
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(2): error C2143: syntax error: missing ';' before '*'
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(2): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(2): error C2059: syntax error: '/'
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(4): error C2143: syntax error: missing ';' before '{'
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(4): error C2447: '{': missing function header (old-style formal list?)
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(14): error C2143: syntax error: missing ';' before '&'
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(14): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(15): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(15): error C2059: syntax error: '{'
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(15): error C2143: syntax error: missing ';' before '{'
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(15): error C2447: '{': missing function header (old-style formal list?)
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(29): error C2143: syntax error: missing ';' before '&'
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(29): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(29): error C2086: 'int FReply': redefinition
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(14): note: see declaration of 'FReply'
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(30): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(30): error C2059: syntax error: '{'
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(30): error C2143: syntax error: missing ';' before '{'
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(30): error C2447: '{': missing function header (old-style formal list?)
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(43): error C2143: syntax error: missing ';' before '&'
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(43): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(43): error C2086: 'int FReply': redefinition
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(14): note: see declaration of 'FReply'
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(43): error C2065: 'FDragDropOperation': undeclared identifier
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(43): error C2923: 'TSharedRef': 'FDragDropOperation' is not a valid template type argument for parameter 'ObjectType'
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(44): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(44): error C2059: syntax error: '{'
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(44): error C2143: syntax error: missing ';' before '{'
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(44): error C2447: '{': missing function header (old-style formal list?)
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(50): error C2143: syntax error: missing ';' before '&'
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(50): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(50): error C2086: 'int FReply': redefinition
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(14): note: see declaration of 'FReply'
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(51): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(51): error C2059: syntax error: '{'
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(51): error C2143: syntax error: missing ';' before '{'
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(51): error C2447: '{': missing function header (old-style formal list?)
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(57): error C2143: syntax error: missing ';' before '&'
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(57): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(57): error C2086: 'int FReply': redefinition
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(14): note: see declaration of 'FReply'
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(58): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(58): error C2059: syntax error: '{'
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(58): error C2143: syntax error: missing ';' before '{'
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(58): error C2447: '{': missing function header (old-style formal list?)
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(63): error C2059: syntax error: 'public'
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(66): error C2270: 'ShouldReleaseMouse': modifiers not allowed on nonmember functions
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(66): error C2065: 'bReleaseMouseCapture': undeclared identifier
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(69): error C2270: 'ShouldSetUserFocus': modifiers not allowed on nonmember functions
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(69): error C2065: 'bSetUserFocus': undeclared identifier
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(72): error C2270: 'ShouldReleaseUserFocus': modifiers not allowed on nonmember functions
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(72): error C2065: 'bReleaseUserFocus': undeclared identifier
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(75): error C2270: 'AffectsAllUsers': modifiers not allowed on nonmember functions
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(75): error C2065: 'bAllUsers': undeclared identifier
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(78): error C2270: 'ShouldUseHighPrecisionMouse': modifiers not allowed on nonmember functions
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(78): error C2065: 'bUseHighPrecisionMouse': undeclared identifier
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(81): error C2270: 'ShouldReleaseMouseLock': modifiers not allowed on nonmember functions
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(81): error C2065: 'bShouldReleaseMouseLock': undeclared identifier
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(84): error C2270: 'ShouldThrottle': modifiers not allowed on nonmember functions
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(84): error C2065: 'bPreventThrottling': undeclared identifier
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(87): error C2270: 'GetMouseLockWidget': modifiers not allowed on nonmember functions
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(87): error C2065: 'MouseLockWidget': undeclared identifier
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(90): error C2270: 'GetUserFocusRecepient': modifiers not allowed on nonmember functions
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(90): error C2065: 'FocusRecipient': undeclared identifier
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(93): error C2270: 'GetFocusCause': modifiers not allowed on nonmember functions
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(93): error C2065: 'FocusChangeReason': undeclared identifier
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(96): error C2270: 'GetMouseCaptor': modifiers not allowed on nonmember functions
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(96): error C2065: 'MouseCaptor': undeclared identifier
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(99): error C2270: 'GetNavigationType': modifiers not allowed on nonmember functions
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(99): error C2065: 'NavigationType': undeclared identifier
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(102): error C2270: 'GetNavigationGenesis': modifiers not allowed on nonmember functions
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(102): error C2065: 'NavigationGenesis': undeclared identifier
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(105): error C2270: 'GetNavigationSource': modifiers not allowed on nonmember functions
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(105): error C2065: 'NavigationSource': undeclared identifier
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(108): error C2270: 'GetNavigationDestination': modifiers not allowed on nonmember functions
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(108): error C2065: 'NavigationDestination': undeclared identifier
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(111): error C2065: 'FDragDropOperation': undeclared identifier
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(111): error C2923: 'TSharedPtr': 'FDragDropOperation' is not a valid template type argument for parameter 'ObjectType'
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(111): error C2270: 'GetDragDropContent': modifiers not allowed on nonmember functions
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(111): error C2065: 'DragDropContent': undeclared identifier
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(114): error C2270: 'ShouldEndDragDrop': modifiers not allowed on nonmember functions
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(114): error C2065: 'bEndDragDrop': undeclared identifier
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(117): error C2270: 'GetDetectDragRequest': modifiers not allowed on nonmember functions
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(117): error C2065: 'DetectDragForWidget': undeclared identifier
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(120): error C2270: 'GetDetectDragRequestButton': modifiers not allowed on nonmember functions
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(120): error C2065: 'DetectDragForMouseButton': undeclared identifier
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(123): error C2270: 'GetRequestedMousePos': modifiers not allowed on nonmember functions
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(123): error C2065: 'RequestedMousePos': undeclared identifier
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(125): error C2059: syntax error: 'public'
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(130): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(130): error C2370: 'FReply': redefinition; different storage class
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(14): note: see declaration of 'FReply'
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(130): error C2146: syntax error: missing ';' before identifier 'Handled'
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(131): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(138): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(138): error C2370: 'FReply': redefinition; different storage class
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(14): note: see declaration of 'FReply'
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(138): error C2146: syntax error: missing ';' before identifier 'Unhandled'
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(139): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(143): error C2059: syntax error: 'private'
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(149): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(149): error C2365: 'FReply': redefinition; previous definition was 'data variable'
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(14): note: see declaration of 'FReply'
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(149): error C2923: 'TReplyBase': 'FReply' is not a valid template type argument for parameter 'ReplyType'
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(14): note: see declaration of 'FReply'
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(170): error C2550: 'FReply': constructor initializer lists are only allowed on constructor definitions
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(173): error C2059: syntax error: 'private'
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(174): error C2255: 'friend': not allowed outside of a class definition
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(176): error C2059: syntax error: 'private'
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(178): error C2550: 'void __cdecl `dynamic initializer for 'RequestedMousePos''(void)': constructor initializer lists are only allowed on constructor definitions
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(179): error C2550: 'void __cdecl `dynamic initializer for 'EventHandler''(void)': constructor initializer lists are only allowed on constructor definitions
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(180): error C2550: 'void __cdecl `dynamic initializer for 'MouseCaptor''(void)': constructor initializer lists are only allowed on constructor definitions
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(181): error C2550: 'void __cdecl `dynamic initializer for 'FocusRecipient''(void)': constructor initializer lists are only allowed on constructor definitions
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(182): error C2550: 'void __cdecl `dynamic initializer for 'MouseLockWidget''(void)': constructor initializer lists are only allowed on constructor definitions
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(183): error C2550: 'void __cdecl `dynamic initializer for 'DetectDragForWidget''(void)': constructor initializer lists are only allowed on constructor definitions
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(184): error C2550: 'void __cdecl `dynamic initializer for 'NavigationDestination''(void)': constructor initializer lists are only allowed on constructor definitions
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(185): error C2550: 'void __cdecl `dynamic initializer for 'DetectDragForMouseButton''(void)': constructor initializer lists are only allowed on constructor definitions
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(186): error C2065: 'FDragDropOperation': undeclared identifier
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(186): error C2923: 'TSharedPtr': 'FDragDropOperation' is not a valid template type argument for parameter 'ObjectType'
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(186): error C2133: 'DragDropContent': unknown size
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(186): error C2512: 'TSharedPtr': no appropriate default constructor available
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\Core\Public\Templates/SharedPointer.h(533): note: see declaration of 'TSharedPtr'
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(191): error C2143: syntax error: missing ';' before ':'
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(191): error C2059: syntax error: ':'
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(191): error C2059: syntax error: 'constant'
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(192): error C2143: syntax error: missing ';' before ':'
    2>C:\Program Files\Epic Games\UE_4.18\Engine\Source\Runtime\SlateCore\Public\Input/Reply.h(192): fatal error C1003: error count exceeds 100; stopping compilation
    2>ERROR : UBT error : Failed to produce item: D:\Unreal Projects\Chasing_White_Rabbit\Binaries\Win64\UE4Editor-Chasing_White_Rabbit.dll
    2>Total build time: 3.00 seconds (Local executor: 0.00 seconds)
    2>C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\Common7\IDE\VC\VCTargets\Microsoft.MakeFile.Targets(44,5): error MSB3075: The command ""C:\Program Files\Epic Games\UE_4.18\Engine\Build\BatchFiles\Build.bat" Chasing_White_RabbitEditor Win64 Development "D:\Unreal Projects\Chasing_White_Rabbit\Chasing_White_Rabbit.uproject" -waitmutex" exited with code 5. Please verify that you have sufficient rights to run this command.
    2>Done building project "Chasing_White_Rabbit.vcxproj" -- FAILED.
    ========== Build: 1 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

Would you be able to provide any of the code that is causing the issues?

If you straight out converted from blueprints then check if you have all modules needed for VR in your build file (your_project_name.Build.cs)

VR needs the Head mounted display module for sure.

Check the line with PublicDependencyModuleNames. It should resemble something like below:

PublicDependencyModuleNames.AddRange(new string[] { "Core", "CoreUObject", "Engine", "InputCore", "HeadMountedDisplay" });

You may have more elements but “HeadMountedDisplay” is needed

you seem to try to use Reply.h

which in the documentation seems to rely on the module SlateCore

be sure to uncomment
PrivateDependencyModuleNames.AddRange(new string { “Slate”, “SlateCore” });
in the build file too.

This might clear up the errors that probably arise from missing modules.