ussnorway: you did nothing wrong except buy a Mac

Messages from GOG.com

Please note MacOS version of the game is currently only available to play via GOG GALAXY 2.0. Offline installer will be added as soon as it's ready.

also note Gog \ Larian account sync is busted by installing this patch i.e, the launcher will think you don't have an account and ask you to make a new one but should re-sync once you sign back in

pipopolam: What does it mean "play via GOG GALAXY 2.0"?

ussnorway: it means Gog is full of shit and that message is from patch 6... they just leave it up

as a Mac user you are a 3rd class player and have to wait
Gog Galaxy Windows users are 2nd class players and Steam Windows comes first

[For you Mac users out there, this update will be live for Mac OS soon]
ref = https://store.steampowered.com/news/app/1086940/view/6047774523923588668