About this app
The problem is that when the customer is browsing your store, there is no visible message letting them know that they have a discount that they can use. And they would have to either remember the discount code or copy it from the email and paste it during the checkout.
This app allows you to link to your store with the discount code attached to the URL. The customer will see a banner that tells them about the discount, which will then be automatically added to the checkout.