SaRaB - the 2% commission means that 2% of all your ad revenue goes to the developer.
If you don't want this, these are my XDK settings, and the vanilla AdMob plugin from Scirra works with these;
XDK Build 3240
Optimise with Crosswalk checked
Cordova CLI Version 5.4.1
Minimum Android API - 7
Target Android API - 23
Crosswalk Runtime Embedded - 16
Then I went Plugin Managment > Add Plugin > Third Party Plugin > then I added cordova-plugin-ad-admob
and everything worked fine.
Hope this helps