Password for access into signed document

(Sorry folks if this is an old, addressed topic.  Could not find it in my search)

For simplicity sake, I combined multiple -- standalone documents  -- each with a signture, into a single Adobe Sign document.

I know need to separate those into separate PDFs.  When I try to do so in my PDF management solution (PDFPen), it asks for a Password... which I never set.

So... how do I determine the password that I "used" when the document was created?

- Andrew