That is the default port for ssh, not FTP. Some FTP clients support FTP over ssh protocol, but not all do, and if your user does not have shell access an FTP client will not be able to login to FTP over ssh on port 22, even if they are allowed FTP access.
FTP is on 20/21, and ProFTPd also provides FTP-over-SSH on port 2222 (which works even if the user has no shell, but is allowed to use FTP).