Try the password used to access the protected functions in the Humax menu (nothing to do with the web interface). The login is 'humaxftp' and unless you've changed it the password is '0000'. Also, be sure that you've turned the ftp server on in the box's menu (Settings - System - Internet Settings - FTP Server) UNLESS you've installed the alternative ftp server available in the enhanced software. If you have installed this, the internal ftp server must be switched off.
EDIT: assuming you are in the right forum, as per af123's question....