Someone commented about this a month ago.
Hoodie responded with:
Oh sorry, I misnamed the folder I think. the "MtE MAC" folder should be the app, try renaming it and adding .app to it, so it's called "MtE MAC.app". If that doesn't work I'll see what I can do.
Person responded back with:
This worked, thank you! Though I did need to also run:
sudo chmod -R 755 path/to/app.app
In order to open it on Big Sur
See if that helps.