Why this happens:
You typed in your passcode too many times

How to fix it:
Bring your ipad to the iPad office [or the ARC, if the office is unoccupied.] We will have to wipe it, which can take anywhere from a couple of hours to a day or so [depending on what else is happening tech-wise.]

Hopefully you setup your Notability backup to Drive correctly, AND your photos and videos are backing up to Drive as well.

HERE’S HOW to check that your backups are actually happening.