Попробуйте использовать ftp_get ()
$local_file = 'filename.txt';
$server_file = 'filename.txt';
$conn_id = ftp_connect($ftp_server);
$login_result = ftp_login($conn_id, $ftp_user_name, $ftp_user_pass);
if (ftp_get($conn_id, $local_file, $server_file, FTP_BINARY)) {
echo "Successfully written to $local_file\n";
} else {
echo "There was a problem\n";
}
ftp_close($conn_id);