I'm thinking perhaps this is not a duplicate of this problem from five years ago since the reported message differs (and the OS has been updated a lot since then): I wrote a review to post for Document Viewer in lubuntu 18.04.1 LTS. It wants me to log in to Ubuntu One in order to post it. It's telling me 'Provided email/password is not correct.' However, this combination is correct, and I even changed my password at login.ubuntu.com in case I might be wrong, and it's still not accepting it.
Why is it refusing to accept my email/password and how do I fix it?
This is a fresh installation from LiveDVD (i386 ISO downloaded with correct md5 checksum and DVD checked for errors before installation, no errors found).