FedEx One Rate
If you are enrolled in FedEx One Rate program, you can choose to use it in Teapplix.
FedEx One Rate is applicable to some of the FedEx ship method such as Priority Overnight, 2Day, Express Saver, etc. And you have to use one of the FedEx package type.
After you have connected your FedEx account with your Teapplix account, you need to expand the Configure Ship Method section at the bottom of the Setup->FedEx page, check those FedEx One Rate options (one for each FedEx ship method and package type), and click Save.
You should see those FedEx One Rate options you have enabled displayed on the FedEx ship method drop down list for the Open Orders.