Coupon Code Field

Step 1: Create a simple form as image in below:

Step 2: Edit Coupon Code Field > Setting Tab > Field > choose Coupon Code type.

Next, click Add Item > fill Coupon Codes > choose Discount Type: Percentage or Flat Amount > Coupon Amount.

Step 3: Edit Total Field > Setting Tab > Field > choose Calculated Field type > add Coupon Code Field shortcode into the box.

Step 4: Your result