Documentation Unclear for Non-Technical Users for WebSocket Server Config

I'm a not particularly savvy user of a managed Nextcloud instance (Hetzner Storage Share). I know a little bit about development but not much.

When I install the app via the Discover page, it says "Whiteboard requires a separate collaboration server to work. Please see the documentation on how to install it." It then links to the ReadMe, where "WebSocket Server for Real-time Collaboration" is not particularly clear on what users using the GUI should do.

This doesn't help me much with the interface I get in the app.

The GUI asks me for a string for the websocket server URL. In the ReadMe's "Configuration" section, it says
occ config:app:set whiteboard collabBackendUrl --value="https://nextcloud.local:3002"

I'm assuming I should just be putting the websocket URL not that exact string(?), but I'm still not sure how to ascertain my websocket URL. The instructions are a little unclear.

The "shared secret" is baffling to me. Again, as a not very technical user, I don't want to mess up anything related to security. What do I put in this box?

Any advice would be helpful, and it might be good to add a little to the documentation for those of us using the GUI.

Start with the README's “WebSocket Server for Real-time Collaboration” and “Configuration” sections, then compare them with the Whiteboard GUI fields shown in the issue. Clarify which value belongs in the websocket server URL field and how users should choose the shared secret. Done means a non-technical managed-instance user can follow the documentation without guessing.