By default, product returns ship with USPS for US based merchants and with Canada Post for Canada based merchants. Shipping labels will be billed to your account by Returnly.
You can leverage your own UPS or FedEx account and shipping rates within Returnly by upgrading your plan. Shipping labels will then be billed by the carrier to your account at your negotiated rates.
Please check Custom UPS and FedEx feature availability and pricing here or upgrade your plan right from your dashboard.