Thanks for reaching out!
When making a return or an exchange at REI we ask that you have a proof of purchase with you. Here is a list of some of the things that qualify as a proof of purchase:
It looks like you have your membership attached to your account here in the community. If you purchased your item with your membership, the customer service representative should be able to look up your purchase for you when you return your item.
Hopefully this helps, thanks!