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 checked that page and the reason it's not submitting was because of this error:
To fix this, remove the form on that page, then re-embed it using the steps outlined on the guide I'm linking below.
Complete guide: Adding-Forms-to-Wordpress-org-Version
It's important that you rigorously follow the guide I linked above as the error seems to be caused by the oEmbed Plugin that you're currently using. If that won't work, then proceed with the steps listed on the guide below.
Related guide: A-guide-to-forms-for-WordPress-users