A LOA from your supplier is not authorization from the brand.

"Do you have written authorization or approval from the brand or this company to list and or sell the products from their company? A lot of companies will authorize a supplier, but in their terms of use, you are not authorized to distribute the materials from the site they were sourced from. These suppliers are typically licensed and authorized for sale to the end consumer, no resale. I would suggest reviewing your suppliers terms of use or terms of service and work with the brand itself to obtain a letter of authorization as this will be required at this point to show proof you are an authorized distributor for the concerned brand. So you are additionally aware, if your supplier tries to issue you a letter of authorization, it will not be accepted. They will only accept an LOA if issued by the brand or rights owner only."