I've reuploaded the game (v3.11) to now include more help on how to run it. Please read:
Once you extract the .RAR file you are left with a folder called something like "MtE.app"
Open up a Terminal and navigate to your app folder:
cd <PATH_TO_YOUR_APP>/<APP_NAME>.app/Contents/MacOS/
(visual help for finding the right file: https://imgur.com/a/BKsVkbZ )
This folder contains the executable file which Windows didn’t make executable. you now have to add the executable flag:
chmod a+x <APP_NAME>
(more help about the chmod a+x here: https://stackoverflow.com/questions/50577473/unity-game-compiled-in-windows-does... )
Afterwards you should be able to run/start the app