For Mass Notification campaigns you simply select the Coupon campaign name from the Coupon campaign dropdown on the first step of the campaign setup page.
For Signup / Anniversary campaigns you need to set the gift type to No Gift, Only Messaging first under gift type. This will bring up the Coupon campaign dropdown, select the Coupon campaign name from the list.
After the Coupon campaign is selected you need to add the Dynamic tag {{{coupon_code}}} in the email editor in the body of the email or in the HTML of the email as that tag will be replaced with the coupon code.
If further assistance is required, submit a ticket to Punchh Support. (For help submitting a ticket, click here)