curl --request POST \
  --url https://api.firstpromoter.com/api/v2/affiliate/referrals \
  --header 'Account-ID: <account-id>' \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "email": "[email protected]",
  "promoter_campaign_id": 123,
  "uid": "<string>"
}
'

{
  "id": 123,
  "uid": "<string>",
  "state": "subscribed",
  "metadata": {},
  "created_at": "2023-11-07T05:31:56Z",
  "customer_since": "2023-11-07T05:31:56Z",
  "email": "[email protected]",
  "promoter_campaign": {
    "id": 123,
    "campaign_id": 123,
    "created_at": "2023-11-07T05:31:56Z",
    "campaign": {
      "id": 123,
      "name": "<string>",
      "color": "<string>"
    }
  }
}