Clean install umbrel 1.21 on iMac

I managed to create a Balena USB (mac version DMG) and I added the most recent umbrel .xz file. Booted holding the option key, Umbrel was installed. Shut down, removed USB, and booted OK to terminal prompt.
Umbrel login:
Entered umbrel, but then fails on password.
I found I can get is as umbrel / umbrel
I was expecting to boot in graphical mode. Any hints?