Def.
Carrier configuration comes into action when you have your own carrier or you have pre-negotiated rates with an existing carrier.
If you have pre-negotiated rates with a carrier, you can add API keys and use that carrier to issue return labels. By default, we set up a USPS account with standard rates for your store which will be used to issue labels if you enable 'Send Label' shipping method from Settings. For more details, see this link:
Now, to add a carrier, we would require your account details based on the carrier that you choose to add. For different carriers, we require different information. The different carriers that we allow are:
Let's go through the process of adding a carrier.
To add a carrier, navigate to Configuration > Shipping > Carrier Configuration