Need help listing an item not in Amazon’s catalog

It has a barcode. I enter in all the info and keep getting this error. Can someone please help me to get around this somehow?

8572: You are using UPCs, EANs, ISBNs, ASINs, or JAN codes that do not match the products you are trying to list. If you believe you have reached this message in error, contact Seller Support with the following information: • Product Name • Manufacturer name • Brand name • UPC or EAN or ISBN or JAN along with GS1 certificate • Non-brand owners: A copy of a letter/email from the manufacturer or brand stating that the UPC or EAN or ISBN or JAN you are using to list this product is valid • Brand owner: Valid and current (not expired) GS1 certificate for the GTIN range(s) used by your listings