Fix Javascript Website Issue

On the checkout page of my website (https://ipanow.com/ipanow-online/ipa-transcription-plans/ipa-transcription-one-month-subscription/sign-up) there is a Javascript that fires when the user enters a coupon code to calculate the adjusted amount due. Currently the Javascript only works when the user is logged in, but it SHOULD also work when the user is not logged in. I have tried to figure out why but cannot. I need someone to help me fix the issue. I will provide login credentials to the selected freelancer so he/she can login to my site to see the difference.