Admin can purchase the “Zipcode Validator” as an add-on to provide the functionality to the user to check whether product delivery in their own area is available or not.
If you have purchased the add-on, you must have AppJetty’s Zipcode Validator extension configured from the Magento backend. For that, navigate to Stores -> Configuration -> MageMob App Builder. 
Frontend (App Builder app)
Once you configured the Zipcode validator and enabled the Zipcode Validator for the App Builder, your customers (the users) will get the Ener Zipcode widget on the Product detail page. 
Using the Zipcode widget, the user will be able to check the delivery availability by inserting that area’s Zipcode and if there is no availability in that area, they will get the not delivering message else get the availability message. 
Note: The user will get both messages that are inserted in the Zipcode Validator configuration.
If the product is not available to deliver on the area of inserted Zipcode, your customer will get the “Add to cart” button disabled during the Checkout.
If the customer is trying to place an order with the shipping address where delivery is not available, the checkout flow will be disabled and highlighted with the alert message.