If you haven't already, sign up for a free EasyPost account by following the steps on their site.

Set up a primary payment method and recharge plan on the Billing page.

Once logged in to your EasyPost account, go to the Account Settings page.

Click "Carriers" at the top, then "Add Carrier"

In the "Add Carrier Account" list, find (or filter by name for) the "Fedex" option and select it.

Fill in your Fedex account information and click "Create"

Once your Fedex account is connected to EasyPost, go to the API Keys page

Copy (or create) a production API Key for use in SKULabs. Treat your API key like a password. It shouldn't be made public on your website or included in emails.

Log into SKULabs and go to settings > Connect a carrier

Select Fedex from the carriers list and paste your Production API Key into the "EasyPost API Key" field.

Select your Fedex account from the dropdown field below, give that account a nickname, then click "Save" to add the account to SKULabs.

(Optional) Once Fedex has been added to your SKULabs account, you can customize which stores have access to it on the settings > View all shipping carriers page.