Merge pull request #6926 from segmentio/mgutten_fb_permissions

Add clarification for permissions/account structure on Facebook Custom Audiences

Author: forstisabella

src/connections/destinations/catalog/actions-facebook-custom-audiences/index.md

@@ -25,7 +25,7 @@ This destination sends audiences, or lists of users, from your data warehouse to
 
 ### Prerequisites
 - A Reverse ETL source already set up. If you don't yet have a Reverse ETL source, follow the instructions in Segment's [Reverse ETL documentation](/docs/connections/reverse-etl/#getting-started). Segment recommends setting an [External ID](#sync-audience) as the primary key for your Reverse ETL model, as you'll need an External ID to remove users from your custom audiences. 
-- A Facebook account with [ads_management](https://developers.facebook.com/docs/permissions#ads_management){:target="_blank”} permissions for the target Facebook Ads Account(s).
+- A Facebook account with [ads_management](https://developers.facebook.com/docs/permissions#ads_management){:target="_blank”} permissions for the target Facebook Ad Account(s). The Facebook Ad Account(s) must also be associated with a [Facebook Business Account](https://www.facebook.com/business/help/407323696966570?id=649869995454285){:target="_blank”}.
 
 ### Connect to Facebook Custom Audiences
 1. From your Segment app, navigate to **Catalog > Destinations** and search for "Facebook Custom Audiences (Actions)".