These are the extensions required to integrate AdMob ads in your appinventor-2 application. You should follow the process mentioned here in AppInventor community post to integrate AdMob ads in your application.
Remember this extension will not work on Kodular, Niotron or any other platform except for AppInventor-2. If you faced any problems in the extension or you wanted to suggest me anything then you can DM me from here. Your suggestions are always welcomed and it will help me to make these extensions better.