What is JotForm?
JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.
At JotForm, we want to make sure that you’re getting the online form builder help that you need. Our friendly customer support team is available 24/7.
We believe that if one user has a question, there could be more users who may have the same question. This is why many of our support forum threads are public and available to be searched and viewed. If you’d like help immediately, feel free to search for a similar question, or submit your question or concern.
I was experimenting this to autopopulate the address field to Billing address by placing the condition and it worked for me with a simple condition. It seems this feature is added recently. I've cloned your JotForm to my account and placed a checkbox as Billing address below the address field from Step 1. Then a condition has been set to fill if the checkbox is checked to update the address field to the payment field.
Please see the following screenshot that can help you in setting up the condition for this case.
You can also check the demo JotForm of your clone here.
If you want, you may clone this JotForm to your account and make necessary modifications.
Hope this information helps. Please let us know if you need further assistance in this regard. We will be happy to help.