I went to desktop mode and into my web browser of choice to download the "game installer" package. I then went to Steam and added the .exe installer to Steam as a non-Steam game. I set the compatibility for it to run to GE Proton 33. I clicked play. The installer will boot and start to install the game to a location of your choice. Once its done installing take that new launcher.exe it created in the install location and add that as well to Steam as a non-steam game. Again, set compatibility to GE Proton 33. You can either launch the game in desktop mode or go back to game mode and play the game. I play the game from game mode. Its part of my Steam library.