To enable auto fulfillment you just have to enable the setting of Auto Fulfillment and it will automatically mark your order as fulfilled in the Shopify panel.  So for next shipment process you don’t need to fulfill your orders manually, whenever you create the tracking number for orders it’ll auto push to your Shopify store and status will get updated to fulfilled.

Let’s walk you through the setup process, 

1. Open app from shopify panel 
2. Click on settings from left side menu bar 
3. Click on Auto Fulfillment option 
4. Then click on the checkbox of , ”Do you want to fulfill orders automatically?”
5. Then you can select either one of the options according to your preference.
   Different options are, Mark order as fulfilled after successfully delivered to customer and Mark order as fulfilled after generate tracking number.
6. Click on Save button