First, I never feel comfortable advising on outlook, as Microsoft has many varieties. However, I had this same problem yesterday. As a guess, I changed OAUTH2 to 'normal password' for incoming server and SMTP server and it worked. I do not know why, but it worked. It's worth a try, as that is a confusing message. Good luck.

Thanks, David

I try, it works

Thank you very much!

You are welcome. I'm pleased it worked. :)