Merge pull request #5557 from segmentio/issue-5317

Clarify how to promote IDFA as an identifier more explicit

Author: stayseesong

src/connections/destinations/catalog/adwords-remarketing-lists/index.md

@@ -12,7 +12,7 @@ The Google Ads Remarketing Lists destination is one of Segment's most popular En
 This destination can send audiences created in [Engage](/docs/engage/) to Google Ads as a [Customer List](https://support.google.com/google-ads/answer/6276125){:target="_blank"}. Once you set this destination up, Segment sends an initial user list of users to the [Google Ads API](https://developers.google.com/google-ads/api/docs/remarketing/overview){:target="_blank"}. As users move in and out of the audience, Segment automatically updates the list in Google every hour. This allows you to run advertising campaigns without having manually update the list of users to target in your Google Ads campaigns.
 
 
-You can send either an email address or mobile device ID (IDFA) from Engage to Google as custom matchers. You can set an email address on the user profile by including `email` as a trait on an [`identify` call](/docs/connections/spec/identify/), as a property on a [`track` call](/docs/connections/spec/track/), or as an [external id](/docs/unify/identity-resolution/externalids/) for the user. If you use Segment’s mobile SDKs to collect events from a mobile app, the user’s IDFA is automatically captured. If you don't use Segment’s mobile SDKs, you can set the user’s IDFA by setting it within `context.device.advertisingId`.
+You can send either an email address or mobile device ID (IDFA) from Engage to Google as custom matchers. You can set an email address on the user profile by including `email` as a trait on an [`identify` call](/docs/connections/spec/identify/), as a property on a [`track` call](/docs/connections/spec/track/), or as an [external id](/docs/unify/identity-resolution/externalids/) for the user. If you use Segment’s mobile SDKs to collect events from a mobile app, the user’s IDFA is automatically captured. If you don't use Segment’s mobile SDKs, you can set the user’s IDFA by setting it within `context.device.advertisingId`. You are also required to collect `context.device.type` and `context.device.adTrackingEnabled` on the event payload. Additionally, ensure `android.idfa` and `ios.idfa` are enabled as identifiers in your [Identity Resolution settings](/docs/unify/identity-resolution/identity-resolution-settings/) in Engage.
 
 When you send an audience to Google Ads Remarketing Lists, you can choose which custom matcher (email or mobile device ID/IDFA) to match with. If a user has multiple emails or IDFAs on their account as `external_ids`, Engage sends the ID that was most recently added to the user profile to Google Ads.