To compile you need the latest version of rust.
Clone the project, and open command prompt in the root of the directory then run
cargo build --release
The dll will be placed in
gmod-filestealer-rs\target\release
Run gmod in 64 bit then inject the dll into gmod.exe
All files are placed in the drive your gmod is located + /stealer/, for example if your gmod is located on your D: drive then it'll be placed in D:/stealer/