If you use a username and password to login there will be a 2 factor code sent to your email to confirm it is really you signing in. Sometimes this code doesn't work though.
Be sure to check your Spam folder. It's normally in there.
Sometimes mail servers just block emails from SigParser. In this case the SigParser support team can turn off 2 factor authentication if you submit a support ticket. Before we turn it off we'll email you to confirm the request really came from you. You also must request it from the email address associated with the user you're trying to turn off the 2 factor authentication for.
Finally, if you are using Google or Microsoft 365 you shouldn't be using a username and password to sign in. You should just sign in with one of those providers instead.