how to set url in admin option page

Question

You can only this link when you register a new post type with the right argument to show it in the admin ui and be available in the menu :

    $args = array(
       'show_ui'            => true,
       'show_in_menu'       => true,
    }
    register_post_type('invitation_code', $args);

There’s no really need to have “page=invitation_code” as you are in an edit page.

If you need to create a special page for “invitation_code”, your need to use add_menu_page() function.