Create an Actalike (lookalike) audience via the Pinterest Ads API from a seed customer list or Pinterest Tag event source

Steps

1. Set up the Pinterest Tag on the advertiser's site (for an event-based seed) or prepare/post a hashed customer list (for a list-based seed)
2. Create the seed audience by POSTing to /v5/ad_accounts/{ad_account_id}/audiences with audience_type CUSTOMER_LIST or VISITOR and the relevant rule fields (customer_list_id, or visitor_source_id/ingestion_source/event)
3. Create the Actalike audience with a second POST to the same audiences endpoint, setting audience_type to ACTALIKE and rule.seed_id to the seed audience's id, plus country and percentage
4. Poll GET /v5/ad_accounts/{ad_account_id}/audiences/{audience_id} until status is READY before targeting it
5. Reference the resulting audience id via the AUDIENCE_INCLUDE parameter in an ad group's targeting spec