I'm currently applying to jobs and one section of this job I'm applying asks for the address of my university. What address should be put down here?
Just put whatever is the main address for the university. It's highly unlikely they'll be writing them a letter, but it does fill in that little box. If you're unsure which address that is, go to the website and find the first contact address you can. If you still can't find anything, pick something like the admissions or records office. If the university has multiple campuses, use the main address of the one you attended, if you prefer.
In short, it really doesn't matter as long as it's an address that's real because they like things completed.
You should use the address of the registrar's office, because this is the only department that an employer would potentially be dealing with. Lots of employers don't even do the job of checking educational credentials themselves - they use a service with people who are experts at getting that information, and the staff at the service will likely have the required contact information already. Much of what you put on the application, beside the name of the school, is just a formality.