Holy mother of god this app is HORRIBLE! It is not intuitive and not helpful. I am just trying to merge PDFs and it's accusing one of them of being certified or digitally signed. Funny thing is, it DOES NOT tell which of the PDFs. I also couldn't find anywhere that could tell if an individual PDF is either certified or digitally signed.
Also, for the good lord, where is the link to download the desktop app? Your UX sucks!