As the title suggests, Lutris is requiring me to sign in to GOG so that it can verify my ownership of the game. If my memory serves me well, I used to be able to simply click on the GOG version and then link it to the installation executable file that I downloaded from gog-games.com.
is it all GoG games or just this game? afaik each game script can be different.
From what I have seen it is every GOG game. You have to install it manually if you get it from gog-games.com or another piracy site.