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.
The upload field has some file types allowed by default; however, you may change this and add the needed file type.
Please take a look on this guide that will provide you with the steps to do it: Which-file-types-are-allowed-for-the-upload-field
Regarding to the max upload size, by default it is 1024 KB (1 MB), but you can also change this by following this guide: Changing-the-upload-size-limit
If after doing this your users are still not able to upload the file, please let us know.