PDF files not being synced by iCloud
iCloud is syncing Word files from one Macbook to another newer Macbook, as it should, but it does not sync pdf files. Also does not seem to be syncing pdf files to my iPhone "Files" app. Is there a setting I need to change somewhere? I'm using Office 2016, which I know is old, but I don't see how that would affect how iCloud deals with pdf files.
(Posting this as a separate question from a previous post about Office 2016.)
MacBook Air 13″, macOS 15.5