FYI, using your commands above seem to work and allow the wizard to complete successfully. I am not able to test to see if it is checking for viruses however until I am finishing setting up which will be a few days.
# systemctl start clamd@scan
# systemctl enable clamd@scan
That means Virtualmin is still failing to start clamd. I thought we’d fixed that in 5.04. Once you have it running and setup to start on boot, I think it’ll work fine. But, we still need to fix that problem. ClamAV is such a frustrating beast, because they refuse to ship functional configuration by default…so distros invent their own, which has changed quite a bit with systemd. I thought we’d sorted it out, but obviously not.