If I were a new rider and someone asked me what I wanted I'd say knowledge and advice. Meaning I'd want to learn from the more experienced riders on the team, get advice on whatever.

In terms of material goods most teams will get some kind of a break if buying from a particular shop or something. They may get discounts on kits as well. I'd ask to be treated like the others on the team, no better, no worse. You're there to learn initially (which will actually force the "teachers" to think about what they know and how to explain it) and later, if you're still with the team, you'll be there to share what you know.

You may be expected to help with an event - all teams are supposed to put on some kind of race each year. I'd ask if it's possible to race in the event even if you work it, unless you don't want to race it. I work our club's cross event but I have no interest in racing it. I've also helped with the club TT, ditto on racing it.