If you search for the app:
Start typing "Gifted" in the search bar and select the app from the results.
Click Add to Site.
Click Allow and Add.
Note: When you add the Gifted app, a page is added to your site. Make sure that the page is added to your site menu and published.
Enable Checkout with Gift Cards
To start letting gift card holders redeem cards during checkout, you must enable the option.
Go to the Store Settings tab in your site's dashboard.
Enable the Let customers pay with a gift card at the checkout toggle.
Gift Card Redemption at Checkout
Your clients will be able to redeem their gift cards in the "Redeem a Gift Card" field under the "Payment" options on your checkout page.