Did you read the message that came with the download? It should say:
I packed it as a .RAR file! On Macs some unzippers can corrupt the files, We've tested unpacking with "StuffIt" and it worked.
If you need a different one, try:
https://apps.apple.com/us/app/the-unarchiver/id425424353?mt=12
This one should be official but we haven't tried it!
If you still get an error (this application cannot be opened), try this:
https://stackoverflow.com/questions/50577473/unity-game-compiled-in-windows-doesn-t-open-in-mac
I hope that helps.