Hi!
When I enable bDebugBuildsActuallyUseDebugCRT in unreal editor (Engine/Source/Programs/UnrealBuildTool/Configuration/BuildConfiguration.cs), then build ends up in a failure.
It can not find debug variant of icu dylib files, because Setup.command downloads them with a different naming convection. (linker searches for libicudatad.version.dylib instead of libucudata.versiond.dylib).
I had to modify two files to get it build and run successfully.
I am not sure I enabled bDebugBuildsActuallyUseDebugCRT in right place or it is even supported to set it to true anywhere.
I attached the patch file for UnrealEngine repository.