My friend and I are new to TripleA, from what I understand there are compatability issues between MacOS and PCs but we have been able to get through 4 turns of G40 emailing the save file back and forth. Unfortunately, now he got an error about it not working on MacOS, and now when he tries to load that save file or our replacement file the play button option doesn’t even work. Any advice?

My friend and I are new to TripleA, from what I understand there are compatability issues between MacOS and PCs but we have been able to get through 4 turns of G40 emailing the save file back and forth. Unfortunately, now he got an error about it not working on MacOS, and now when he tries to load that save file or our replacement file the play button option doesn’t even work. Any advice?