I was taking a gander at the nextcloud Pi video.. it seems the omv-salt command is missing on my machine. It's definitely OMV 5, so I'm assuming something is weird here... It seems to be this way on both my virtual install, and my server install, but both are running fine.
root@openmediavault:~# omv-salt deploy run fstab
bash: omv-salt: command not found
root@openmediavault:~#