If you listed your tickets for sale prior to August 16, 2017, you would have selected that you have either "PDF E-tickets" or "Hard-stock Paper Tickets". If your tickets sell, you will be expected to provide the tickets in the format indicated. More information about delivering tickets by uploading etickets or via UPS can be found here.
Listings created after that date do require barcodes to be entered. If the tickets sell, the barcodes will be reissued and etickets with the new barcode will be sent to the buyer.