I had the same error, tired multiple browsers, systems, even networks, disabled all these security settings and it was still a nogo. I also verified I didnt already have an account with the email I was using by attempting to sign in and it said that no account existed.
Ultimately a total shot in the dark saved me, I cleared my cache and tried a different email completely, that worked first try. Hoping this saves someone else hours of frustration right before the tax deadline!
