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 cloned one of your forms and was able to connect and authenticate it with my Salesforce account without any issue.
The actual Salesforce integration seems to be working properly. This suggests that there might be an issue with your current Salesforce credentials. Please do check your credentials and your user account to see if there are any limits on it. You may reset your security token with the help of this guide: Reset Your Security Token.
I would also suggest to contact Salesforce support team on their support page here: https://help.salesforce.com/home.
Please let us know if you need further assistance.