Hy,
there is a bug in the FTP login function.
In File cdn-sync-tool/lib/Cdn/Ftp.php on line 39 you have to change
if ( !$this->resFtp = ftp_connect($this->credentials["hostname"],$this->credentials["port"]) ){
to
if ( !$this->resFtp = ftp_connect($this->credentials["server"],$this->credentials["port"]) ){