Note: Not registered with FedEx yet or don't know your developer credentials? Simply follow this quick guide from Shopify.
Adding your FedEx credentials to Store Pickup + Delivery
Open Store Pickup + Delivery and head to the Rates Page. Scroll down the page to the Shipping section and select the Advanced Options
From the pop up modal select FedEx
Check Enable FedEx rates and enter your Password, Account number, Meter number and API Key.
Important: The Password is unique to your Meter Number and it's not the same as your FedEx account password.
Once entered simply Save and your Fedex rates will be active via the shipping channel of the app!