How to enable Secure View for tagged files in group folders

I’m having a hard time trying to accomplish something that seems possible, but maybe I’m missing something else.

I want to enable Secure view for tagged files as “confidential”. The tag is visible in the collaborative tags section, and I have tagged a file shared through a read-only group folder. The group is Everyone, a virtual group created by the Everyone group app.

I have set up Collabora, and it works for public share links. The watermark appears as configured, including a user name. As it seems to only work with public links, it shows the text “Anonymous user” using the userDisplayName placeholder.

What I want to achieve is to disable downloading and direct view by enabling Secure View through Collabora for internally shared files, so any document supported by Collabora will have the watermark identifying who is viewing it. In this way, leaks of confidential information can be deterred or, at least, traced back to the user.

Another way would be to be able to disable downloads in the shared group folder or just an internal shared folder, but I don’t find the option without using public links (they defeat the idea of the placeholder in the watermark).