Also, if this game is installed on a separate drive or mount, then be sure that the mount is mounted with your user and group, not root.

This can be done like so: https://unix.stackexchange.com/questions/204641/automatically-mount-a-drive-using-etc-fstab-and-limiting-access-to-all-users-o

cd "~/.steam/steam/steamapps/common/Divinity\ Original\ Sin\ 2/"
mv ./bin ./bin.bak && ln -s DefEd/bin bin && cd bin && mv ./SupportTool.exe ./SupportTool.bak && ln -s EoCApp.exe SupportTool.exe