I just completed all the requirements to distribute my game on the Mac and it was def not easy peasy, it's far more involved than getting the Windows version going.
You need an Apple developers account, you have to set up developer and distributor licenses and the app need to be signed and notarized to run on macs other than your own. You also need to research how to set up GameMaker and XCode to make everything work correctly. I can't imagine doing all of this on a computer that wasn't right in front of me, I think it would be near impossible remotely- you'd have to rely a lot on your friend having any desire to help you figure it all out. I'm lucky that my gf has a Macbook Pro, that's what I used to get my Mac version compiled. Oh and you have to pay Apple $99/year to distribute your game.
Point being this isn't Windows where you just have to load up your project and hit compile. How much does your friend want to tinker around with the inner workings of being an Apple developer? I have to be honest I hit roadblocks in the process that took many hours to figure out.