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.
If you are integrating your Form to Dropbox, you'll need to grant access for it so that the submission data including the uploaded files can be directly forwarded to your Dropbox folder, this will require a read & write access. You can check this guide to see the process of integration: http://www.jotform.com/help/77-Upload-to-Dropbox-with-JotForm.
You can also remove the integration to Dropbox.
But for you to use Dropbox, you'll need to JotForm to access the Dropbox, this is a normal process when integrating apps. Rest assure that this is a secure connection.
I hope that helps.