File browser access to docker compose appdata dir

I'm missing some vital information re. the File browser.

1. I've created three users in OMV (appuser, alice, bob), but none of their credentials allow me to pass the File browser login

2. In order to get RustDesk running like old again, I need to restore some key files from my previous RustDesk setup into appdata/rustdesk/data. What do I have to do to gain access to the docker related dirs?

File Browser settings:

User settings (appuser only)

Access rights on share appdata (appuser only)

I did manage to get the replace the RustDekt key files using WinSCP. RustDesk server is up and running again, using the same old security key.

Still puzzled though by the File Browser's login behaviour. Where would I find a manual/guidelines on using the OMV File Manager?