curl --request GET \
  --url 'https://{domain}/api/v2/network/aff-billing/balances/{affiliate_id}?api-key='

{
  "status": "success",
  "code": 200,
  "name": "OK",
  "message": "<string>",
  "info": {
    "billing-affiliate-balance": {
      "currency": "<string>",
      "approved": "<string>",
      "pending": "<string>",
      "due": "<string>",
      "available_advance": 123,
      "breakdowns": [
        {
          "breakdown": "<string>",
          "values": {
            "approved": "<string>",
            "pending": "<string>"
          }
        }
      ],
      "due_by_currencies": {},
      "balance_by_currencies": {},
      "referral_balance": "<string>"
    }
  }
}