Larian Studios Forums Divinity: Original Sin 2 Divinity - Original Sin 2 - Bugs & Technical Problems macOS currently known issues and limitations

You should be able to run the game from Steam in a different OSX account without needing to re-install, or you can browse to the install folder in Finder and launch the game with or without Steam running. In Steam, right click the game in the library, select Properties, switch to the Local Files tab and click the 'Browse Local Files...' to open Finder at the install folder.