Trying to set up multiple email accounts. The first one worked.

Interestingly the account hub you disabled has until now only been active for the first account added. While there is a lot of information on previous topics hare to disable the hub, generally it is not the issue. Thunderbird [https://www.thunderbird.net/en-US/thunderbird/146.0/releasenotes/ 146 included many improvements] to the hub so disabling it should not be something you do until it is proven to be the issue. Unfortunately logging in the an email account in a browser no longer even confirms you know the password. Things between applications and webpages are so different now that the login processes often have not even a vague association. Most folk that get this error also have issues with their antivirus or it's firewall component. Those using the Norton product get far more exposure in this forum than the Norton product popularity would suggest. Then there is the issue that some mail providers require you to enable access outside of a browser, so lets start with what antivirus you use and do you get the same issues when you disable it. They also often block access if there are more than a couple of failed login attempts. So a failed setup can automatically lock setup out for 24 hours depending on the provider. Folks are often using a VPN these days. Unfortunately some providers will not allow access to mail accounts/servers while you use them. Just another hurdle placed by well meaning folk saving you from yourself. Who is the mail provider? Given that Gmail and Outlook along with others that use oAuth authentication make up perhaps the majority of mail accounts being added to Thunderbird do you have cookies enabled in Thunderbird?