Annotate PDF Stored In SharePoint & Save File

Users are unable to annotate on a PDF that is stored in a SharePoint Online document library. When they annotate on a PDF using Microsoft Edge and click save, they are prompted to select the save location in the file explorer (instead of just being able to click “save”) and confirm the changes to the file. The featured covered in this video, (link here) does not seem to be available to our users. Specifically, the "Annotate" button does not display for any user within our environment.

The use case for this is that our users need to mark up specific content in PDFs with text, notes, drawings etc. In the current state, users open the file that is hosted in a SharePoint document library, annotate on it using Microsoft Edge and then when they click save, they have to select the save location. They've been instructed to sync the library so they can access it in the File Explorer but, when they click save, it doesn't automatically open the library for which the file is stored in the File Explorer. The users have to navigate back to the file destination which is sub-optimal.