PDF file "is damaged" trying to open in Books

I have some PDF ebooks I would like to open in Books. They open fine in Adobe Acrobat (my default app for PDFs, which I need to keep as my default PDF open setting for work reasons), and also in Preview if I select that from ctrl + click > "Open With."

However, if I try Open With > Books, or go to Get Info and change the "Open with" there to Books, and then try to open it either from the Finder or from Books after importing it, I get the error message "XXXX.pdf is damaged and can’t be opened. You should move it to the Trash." When I hit cancel in that popup I get a secondary error, "The application “Preview.app” can’t be opened. -128".

For the one file I'm mainly concerned about I have tried: downloading it from the site again in Safari; downloading it from my Dropbox and then my Drive; and using Preview to export it as a new PDF and try to open that. I tried a solution from another answer about using a terminal command to remove the "quarantine" attribute, and that also did not work. When I go to Security and Privacy I can't access Gatekeeper settings even after clicking the lock and entering my admin password (which may be a whole other problem, who knows).

I can open it in Books on my iPhone fine, but I really wanted to be able to read this file in particular on the bigger screen on my Mac since it's designed to be viewed in a 2-page side by side display. (And I realized while trying this that it throws the same error for a number of other PDF ebooks I've imported but hadn't tried to read yet.) Is there any other option to get it to trust the files?