If you don't already have your own UPS or FedEx carrier account, you can create one online in a matter of minutes. UPS has the easiest sign-up process and is the simplest to link.
You can add as many carrier accounts as you'd like. The more accounts you add, the more options buyers will see during checkout. DHL Express service is fast but more expensive than ground services, so we recommend starting with UPS and/or FedEx before adding DHL. The process to connect a DHL account is also more complicated and requires you to register via the DHL API Developer Portal. If you need any help with that process, please create a support ticket.