The account has been blocked, due to too many failed login attempts.
You must wait ~ 24 hours. Disable all devices and software which might try to login with username and password (there are actually not many, all of the official plex servers and clients are using ‘token-based’ authentication). Most infamously known for this behaviour is the old PlexWatch software.
And of course stop all attempts to login manually.
Many attempts, with even weeks of waiting between attempts, my account never generates an email for resetting password.
How can we fix this? I’m wasting money on a plex monthly pass, and would like to purchase lifetime, but i cant even add a new user or setup plex on my new phone at the moment.