Did you get an email from the AOA match on how to register? They give you your ID number in that email. If you have registered for the match, you match code number is the same as your AOA ID number (at least mine is). If you haven't received any of this information I would contact your school and see why you haven't been sent information for how to register for the match.
Also.....if you are an Osteopathic student you have had an AOA ID since your first day of school. It's just your 6 digit membership #.