what are encrypted notability notes in icloud and how to retrieve

My notability notes are suddenly stuck in iCloud, they won’t show in my Notability app, but they are still in iCloud and all the notes have become encrypted files. I can’t switch on my iCloud syncing in Notability, doesn’t allow me to do it. Says that I have to do something in the settings, but everything related to Notability on iCloud is on.