JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.
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.
Can you please share the URL or ID of the form you're referring to?
For successful payments, Authorize.net should send confirmation email automatically to your users once payment was made.
If you are referring to the Autoresponder in JotForm, then you need to create one in order for your users to received a confirmation email. Here's a guide on how to create one: https://www.jotform.com/help/26-Creating-a-Form-Autoresponder
Hope this helps. Let us know if you have any questions. Thank you.