Hi. I am not familiar with the phrase Custom Post Type. I probably know it as something else, but have never used it.
The plugin enables you to set permissions so Editors can only edit, not create or delete pages. I create the page as Admin, but set them as the owner (author).
When they login, they can only see their own pages. If you use the sister plugin, they can only see their own media as well.
The plugins can set or deny any permissions you choose and turns WP into a very useful multi-author type CMS. No need to have a separate installation for each Editor.
Well worth installing and having a play to see what it can do. Do a full backup first and if you don't like it, restore the backup, or just delete the plugins.