I've ftp the generator folder, create sitemap.xml, sitemap.txt, ror.xml and changed thier permissions to 666 as what manual guide.
I've changed the data/ folder permission to 777
Once i try to save the configuration at [external links are visible to admins only]
the page shows
You don't have permission to access /generator/index.php on this server.
Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.