There are always lots of hangers-on at a convention, and far more than just the delegates get a floor pass.
Even if you don’t get into the convention hall, you might want to go to New York to attend the various parties and hospitality suites. This would be a great experience for you.
To get credentialed, the best place to start would be to contact the Republican National Committee representative for your state. Forget working throught the College Republicans on this - you’ll be a small fish there.
Drop me a line at my email address if you need further help.