The Helios4 is supported by Armbian, not Raspbian. Go the Armbian download page -> here and get the image for Helios. (Get the Stretch version because OMV5 for Buster is not ready yet.) Read the Armbian Doc's and install OMV from armbian config
I am sorry, mistype. Sure it's armbian stretch, I take note about strtch and OMV on download page.