Getting packages to my dorm

Theres a bunch of posters I really wanna get on Redbubble but if I buy them they’re gonna sent out after I’m already in my dorm. So I’m trying to see if I can get it mailed to an RSA, but looking at the page they have it says they won’t accepted unauthorized vendors. Idk what vendor they use and the pages Redbubble has on shipping just says they use “one or more 3rd-party fulfillers” which doesn’t help me in the slightest, which is great.

So basically TLDR, has anyone bought and shipped stuff from redbubble and how did it go? Did the RSA accept it, and if not were you able to get your stuff?