“Exclude Pages or Posts” means to allow a specific post or page to be accessible via their respective URL’s. The maintenance page will not show a site menu, so a person has to have the post or page URL to insert into the URL text field of the browser to access it.
To allow access to a specific post or page via their respective URL’s when maintenance mode is on, you must select each post or page individually in the respective text field box provided by the plugin.
When you insert the cursor into the post or page text field box, it will list all posts or pages you created. You can select all of the posts or pages, but only one at a time to do it. The text field box will list all posts or pages you selected as individual label boxes that have “x” to it. (yea, they need to create a “select all” feature).
To disallow any URL access to any of your posts or pages when maintenance mode is on, then the respective text field box must be empty.
Does that help?