Just checked and it seems like their Release file on the repo is still marked with ovm6 while the package you get when installing is omv7.
Tried to build an image with omv pre-installed, but throw a bunch of errors, so no idea if it works. https://fi.mirror.armbian.de/.testing/Armbian-unofficial_25.02.0-trunk_Rockpro64_bookworm_current_6.12.9-omv.img.xz
If not grab a standard rockpro image ( https://dl.armbian.com/rockpro64/Bookworm_current_minimal ) and proceed according omv docs: https://docs.openmediavault.org/en/stable/installation/on_debian.html
Keep in mind that omv heavily messes with the system, so if anything breaks after installation (like network access or even boot) we cannot help. This is userspace.
AlexVS got a reaction from Igor in Armbian with preinstalled OpenMediaVault (OMV)