Obtaining Advertising ID's

Apps that target the Google Play Store must use the Google Advertising ID (gps_adid) to identify devices. You need to add the play-services-ads-identifier AAR to your project to access the gps_adid.

Google External Dependency Manager

If you are using the Google External Dependency Manager plugin, add the following to your Dependencies.xml file:

<androidPackages>
    <androidPackage spec="com.google.android.gms:play-services-ads-identifier:18.0.1" />
</androidPackages>

To install the ARR manually, download it from Maven and add it to the Assets/Plugins/Android directory.