finaly, add this plugins ONE by ONE
if you want to add Admob plugin, use this githubs because you are going to have build error if you associate the cranberry plugin with the OneSignal plugin
" > Error: more than one library with package name 'com.google.android.gms' "
so the solution is to install this admob plugins and NOT cranberry :
it's the same as cranberry plugin but modified to avoide the build error.
this step is very important !!
now you must BUILD you app, INSTALL it in an android device and OPEN it (don't forget to open internet connection on your device)
this is very important if you want next steps to work