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 am not sure if I have understood your question correctly. Do you mean to say that you want to specify what kind of file type users can upload?
Yes it is possible to allow the type of file in file upload field by adding file extension that users will be able to upload. https://www.jotform.com/help/29-Which-file-types-are-allowed-for-the-upload-field
" I.e say the form has to xxx details in it and only then they would be able to upload it." - I would request you to please explain your requirement a bit more in detail with an example and we will surely help you.
We will wait for your response.