Linux too much size after build from source

This is the first time I meeting with the Unreal Engine. I downloaded source code and compiled the engine in Linux with “Setup.sh” file. It downloaded about 5.7 GB size of dependency files before compiling.

Checking dependencies (excluding Win32, Win64, Mac, Android)...
Updating dependencies:   0% (0/30405), 0.6/5738.4 MiB 

But after compile succeed, the installation folder takes 51 GB size on my disk. Why size is too much? Which folders I can delete safely to reduce the installation size?