Simply download Gluffy Manager

Find your games local files

Make a new folder

Extract fluffy manager into new folder

Add mod manager.exe to steam by right clicking

Then go to steam and search for mod manager

In properties then compatibility make sure to have GE proton

Now you can launch the mod manager

Now select the game

Then find the exe by going to common and finding the game folder then clicking the game exe

Now go back to the folder you made for mod manager then go to Games and then choose your game to mod