Plugin may require some small set up action in order to compile in your device with no issue. If plugin isn’t installed the settings window will be opened automatically in the Inspector view. It for some reason it wasn’t opened after you imported the plugin, go to: Window → Google Mobile Ad → Edit Settings
And just press Install Plugin button. If the installation was completed successfully you should see the message as on the picture below.
Plugin should play nice with all other IOS, WP8 and Android plugins. If you found any conflicts feel free to contact support team.