Unreal's Lumen Folder Path

So I downloaded Unreal’s source code from github. Now I’ve already read some path tracers source code (example Blender’s Cycles). I’m intrested on finding out how does unreal achieve real time graphics.
(I know the basic differences btween ray tracing and pathtracing - what I want is a folder path example: D://User/Unreal/Lumen/… does anybody know the path? Do they include lumen’s code? (they probably do since you can build and run unreal engine from just downloading the source code)).
Anyways if anybody knows it would help a lot.