Working as a sub is pretty common here for part time work, especially right after graduating college. The requirements aren't very high but the application process is pretty involved and makes you supply written references from everyone you've worked for over the last three years. Each time they do this I have to re-upload all the documents, fill out 20 or so sections on the online app, wrangle my old supervisors to do their portion again, and re-do the same in person interview. I can't think of any reason why they wouldn't hire me, and none of my friends who've subbed have gone through this.