Download editable version of a template

I have set up a template in Adobe Sign, but now want to edit not just the fields, but the underlying content of the template. As I don't have the original document that was uploaded to create the template, can I download an editable version from Adobe Sign? The two 'download PDF' options in Adobe Sign provide a PDF which is certified by Adobe Sign and so cannot be edited. Is there another solution? (The same issue arises with a web form.)