Xmap is easily installed as any Joomla component. That should be done through your site's backend.
Navigate to the Joomla administrator login page:
Once you log in, you should open the Extensions -> Extension Manager section and click on the [Browse..] button in the Upload Package File section. Navigate to the same Xmap file you have downloaded earlier and select it. Then click on the [Uploap & Install] button to start the installation.
At the end you will see a notification that the component integration was successfully completed.
At this point, Xmap is installed now you need to create your first sitemap and publish the extensions you want to use.
By default, all Xmap extensions are disabled, you will need to enable each extension you want to use by following this steps: