Wonder.

I wonder are there any student residences (or just something similar to student residences) in Munich that accept people who are not students / not from a university?

the short answer is "no".  On-campus student residences are explicitly for students who are NOT from Munich.  Off-campus student residences technically don't exist, but there are many WGs (apartments for multiple flatmates) who only rent to students (although unless they explicitly say "only for registered students" and you're a student-minded/-aged person, you can still try).

Have a look at http://www.wg-gesucht.de/