Hi Shrooblord,
Thanks for your reply. I think I know what happened. My Xcode tool was set to build “UE4 - Mac” - which, I am guessing, tried to build the UE4 editor as well. I believe on Macs, you can only build the game. So when I changed it to build “Mygame - Mac”, I was able to build successfully. So 's answer - now that I am reading it more carefully! - is correct.