This plugin allows you to insert categories to pages too and not only to posts (whitout add new category) . To view the categories in your blog you have to add function to your themes, please see WP the documentation.
When you activate the plugin it just works adding the page editing form.
To view the categories in your blog you have to add function to your themes, please see the documentacion por information.
Visit: http://www.g-innova.com.ar/comunidad/aporte/wordpress-plugins-categories4page/