If you’re using a Raspberry pi just hit the ALT key and a menu will pop up at the top… “File->exit”
you can exit that way…

“How can I download my own repository?” -> go read up on github that will help you… it’s usually git clone or you can just use a browser to go to github and choose ‘download’.

As for changes… I wouldn’t suggest that because if there’s an update to MM all your changes will be gone. Not really sure what you’re trying to do here your information is very vague.

At any rate, hope that helps… I’m off to eat dinner with the family.