New Amazon Seller

I’m trying to get a seller account set up and working for the first time. We are actually only using Amazon for fulfillment, which is why we are trying to use FBA, but everything we try to add requires authentication. We have a Professional account. Where are the products that don’t require authorization or an invoice?

Alternatively, is there anyone US based that could provide inventory and fulfillment for a large selection of products that would be appropriate for a wish list site?