I have this plugin working really well on 3088... The only thing you need to do is add it using the intel-xdk.config.additions.xml file. Add this
<intelxdk:plugin intelxdk:name="https://github.com/cranberrygame/cordova-plugin-ad-admob"
intelxdk:value="https://github.com/cranberrygame/cordova-plugin-ad-admob" />
Note: Remember to remove the plugin from plugin manager.
This is working on IOS and Android.