Accounts>Sign-in>Security key

Hello from a clean install of 20H2 with excellent help from this forum.
Have local single user admin account with a password.
Now trying to use a Solo Fido 2 key.
So went through Settings>Accounts>Sign-in-options>Security key.
First attempt failed because key was plugged into a not always-on usb port (I assume ... as key was refused as not being acceptable).
Second attempt in an always-on port worked.
The key is the type that has a green to red led with a physical touch button.
Also set a key pin.
All accepted.

So restarted and tried to use key but could not get past the normal password box.
Tried key but it had no effect.
There is no "Hello" PIN on this machine, just the user account password.

Any advice gratefully received as I would much prefer to use my key as default method with any other method as secondary/back-up.
Paul

EDIT:
Cannot be done.
Cannot use local account.
Enterprise only.
END EDIT: