Help: MacOS publishing for distribution outside of Mac App Store

Hello,

I'm looking for support from anyone who has published a MacOS game using GameMaker Studio 2, for free distribution on indie sites like itch.io.

I've never published a game before, and I'm finding that the tutorials I come across online don't exactly match what I'm trying to do.

I have registered on the Apple Developer programme, downloaded Xcode, had a go at certificates, team ID's, app ID's, done something in keychain and tried creating an executable in GameMaker Studio 2, but when I send it to another computer it wont open, giving the message "unable to find game!!:".

I don't understand the thinking behind the process (or really even know what most of the above paragraph is about), so realistically I may have made mistakes at multiple points along the way.

If anyone can advise me I'd be very grateful.

Thanks,

Fergus.