Add notes to pdf files for each student individually in Wordpress

I need your help please I have an educational WordPress site with a group of students What I want is to include pdf books on the site with the possibility for each student to add the notes he wants to the book, so that these notes appear only for this student and for the director only, perhaps the system will create a copy of the book on the server for each student, I have no problem with this solution If he is the only one. The important thing is that I want to add a feature that allows my students to add notes to pdf files for each student individually Thank you very much