This documentation is not using the current rendering mechanism and is probably outdated. The extension maintainer should switch to the new system. Details on how to use the rendering mechanism can be found here.
One may insert the plugin within a content page. Choose "Insert Content", then "Generic Plugin", afterwards the "Table of Contents" will be available at the Plugin Tab. Save the new content element and take a look at the frontend to see the table of contents.
Target group: Users