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 can see that you already reached the submission storage limit which is 500. The error refers to the number of Total Submissions Storage. It is not referring the the monthly submissions.
Under the Free plan, you only have 500 total submission storage. It means that you can only store up to 500 submissions in your account. You need to delete some submissions in order to free up your submission storage. Here's a guide: How-to-Delete-Form-Submission-Data
Let us know if you have any questions. Thank you.