It disable default Post Editor and let users like Authors and Editors (not Admin) to write posts only using custom fields.
It disable Post editor for Non Administrators and let you create posts only using Custom Fields (remember to configure them first!) It uses: if ( ! current_user_can( 'install_plugins' ) )
Actually there is no Admin Panel for this plugin if you would like to change minimum permission or role you'll have to change it manually via FTP