Can I download all submitted documents (from all submissions to my form) at one time?

You will need to have ruby installed on your machine. If you are on a Linux/Mac, it is most likely that you have it pre-installed, and for Windows you will need to do manual installation. http://rubyinstaller.org/

We have this File Downloader App that needs a Ruby Application installed to your computer and a single terminal command to download your form files at once.

http://apps.jotform.com/app/file_downloader 

The instructions on how to do this are posted on the App Description section. Please check it and let us know if you need any further assistance.