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'm unable to find your form on the website you have provided. Also, I'm not sure how exactly would you want your form to be pre-filled, can you help us by explaining that further, please?
We will wait for your response. Thank you.
By the way, if you would like to use PHP codes to your form, I would suggest you embed the form using its Full Source Code.
Also, Here's how you can Send-POST-Data-From-JotForm-Using-PHP-in-Custom-Thank-You-Page
Let us know if you need any further assistance. Thank you.