Is there a plugin or any idea how I could provide an area where clients can view a list of and download files with individual password protection?
I could imagine having user pages with individual passwords, and files are attached to each user. Is that a feasible approach?
Yes, but files are still accessible via the media folder if pages are protected.
On top of protecting those pages (Restricting access to your site | Kirby CMS), you would also need a files firewall: Protecting files behind a firewall | Kirby CMS
OK, thanks. I found and decided to use the Locked Pages plugin, for it is easier to use as I just need a simple login and not full blown users (and require an email address). Now I just need to figure out how to protect the files behind a firewall without user status.