If you tried the WebFTP method in my first post, it's not affected by DNS propagation.
Using the ps### hostname isn't reliable because they might move you to another Private Server.
I know this sounds redundant, but double-check the Username in the Manage Domains section and reset the password.
There's also the possibility that the user isn't an FTP account, but it's SFTP only. Check the Manage Users section to see what access the user has. I think SFTP is always enabled, so set Cyberduck to use SFTP for the connection instead of FTP.