since i am new to this so bothering u guys :)
i have dont this but adds are not showing when i export debug.apk from cloudbuild option of construct 3
added MobileAdvert plugin
set application and publisher ID in fields
in event sheet added this
system > on start of layout
> MobileAdvert > is configured > MobileAdvert > create banner advert "have put banner id here" size:smart portrait show:true
> MobileAdvert > Show the current banner advert