Enable the Coupon Window in My Store's Checkout Pages
When using gift certificates or promotional coupons on your store, shoppers will typically enter the coupon code on the view cart (or during the checkout process) using the "Coupon" field located on those pages.
If you plan on using gift certificates or promotional codes for your store, you can enable the coupon field to appear on the store's pages by following these steps:
Log into your Shift4Shop Online Store Manager.
Using the left navigation menu, go to Settings > General > Store Settings.
Click on the Display Options tab at the top of the page.
Under the "Global Options" section, ensure the checkbox labeled "Hide Coupon" is not checked off.
Click Save at the top to commit your changes.
These actions will enable the coupon code field on your store's pages.