When it will released for 5.0.5 openmediavault? Then 5 omv came out in August, there is no urbackup server for it yet …
The urbackup plugin is provided by omv-extras. There will be no plugin for openmediavault for OMV5 from omv-extras. You will have to use urbackup in a docker or install it on Debian along openmediavault