Tutorial on this address is old: https://aerogear.org/docs/unifiedpush/aerogear-push-android/guides/#android-app

The part "Your first Android/Push App" uses older version of library.

For example this is no longer valid:
import org.jboss.aerogear.android.unifiedpush.PushConfig;
import org.jboss.aerogear.android.unifiedpush.Registrations;