When a webpage prompts for a coupon code and I don't have one I don't complete the order.

Thank you for your feedback. Is not actually related to coupons, but rather the my.hubitat.com login session has expired. On the bottom of the page, please click log-out, then log back in to see if that resolves your problem.
I believe he's simply asking for a coupon code. he said "don't" ... not "can't". 