Hello my dear fall guys hacker
To install this tool you need to do a few simple steps 

1. Get bepinex bleeding edge build (for unity il2cpp win-x64)
Could be this one: https://builds.bepinex.dev/projects/bepinex_be/738/BepInEx-Unity.IL2CPP-win-x64-6.0.0-be.738%2Baf0cba7.zip

2. Once it's downloaded open it and put all files from .zip in your Fall Guys folder (the folder where the game is installed)

3. Once everything is in place find FallGuys_client.ini file in your fall guys folder and open it (it could be just FallGuys_client (without game icon) if you have file extensions turned off)

4. In that file change start_protected_game.exe to FallGuys_client_game.exe

5. Now go to BepInEx folder (that you put into your Fall Guys folder on step 2) and open it
If you already have plugins folder there just put FG_Desktop_Cheats folder from here into plugins folder 
If you don't have plugins folder create it and do the same thing 
(overwrite files if it asks you to do so)

6. That's it, now just launch the game VIA THE LAUNCHER (or shortcut) and everything should work 

If something doesn't work or you don't understand something DO NOT ASK FOR HELP. This tutorial explains EVERYTHING you need to do, if you still don't understand it it's just not for you.