You can use Google AdSense without installing an extension. Using AdSense requires the following steps:
1.Create a Google user Account and follow the instructions for creating your AdSense settings. In the end you will have a java-script. Copy the script and save it into a file for later use.
2.Log on to the back end of your website with the superadministrator account.
3.Go to Site > Global Configuration and change the default WYSIWYG editor to 'editor – no editor'. If you don't change the default editor tot no editor the WYSIWYG editor wil change the java script, even if you edit the HTML source.
4.Go to Extensions > Module Manager and create a new module instance of module Custom HTML.
5.Paste the copied java script into the custom output and fill in the other parms like title. Save the module instance.
6.Go to Site > Global Configuration and change the default WYSIWYG editor back to what it was.
There are a lot of extensions for implementing Google AdSense. Maybe some of them can be useful if you have specific needs. But if you just want to use AdSense as it is you don't need them.