If anyone else is having troubles with the Mac files become broken after the upload on itch.io, here's an easy solution:

:whitecheckmark: Archive the .app file before the upload.

Just found out that itch.io's auto-archiving system is somehow broken and Mac files crush after being downloaded and unarchived. So you should archive the files by yourself to avoid the troubles and crushes.

If you have the Mac version of your game and hosting it on itch.io, please, download it and check wether it works or not, be safe from the long minutes of panic and frustration.

:video_game:

Good luck.