The ShipStation Checkout Rates Option sends shipping rates to Wix to display during checkout.
After you have set up your Checkout Rates Options within ShipStation, log in to your Wix account to enable ShipStation to send the delivery options to your store checkout.
To turn on Checkout Rates Options in Wix, go to
Settings > Store Shipping.
Click on “Edit Shipping Rule” for the Shipping Region for which you want ShipStation to provide rates:
Scroll down and click the slider next to ShipStation to enable it: