I am getting a similar error message, but with a Mac. I am re-enrolling a MacBook Air under Big Sur that has just been wiped. The error message is "Invalid Network ID," and it asks me for a Username and Password. I have no idea what Username and Password it might be asking me for, as the machine has been completely wiped and has no accounts set up on it. I had previously removed the profile from Meraki, and then removed the Meraki assignment from Apple Business Manager (though I tried it first before doing that).
Any suggestions for why this message might be appearing, or what it is asking for? All the messages I see online about this issue refer to mobile devices -- this is with a Mac.