Looks like that documentation page is wrong. Please post this as an issue in Issue Tracker (http://www.ubercart.org/issue) so that it will be seen by the people who can fix things.

You can use the Uberinstaller (http://install.ubercart.org) or install manually. If you install manually you will need to first install Drupal (http://drupal.org/) then install Ubercart (http://drupal.org/project/ubercart).