curl --request GET \
  --url https://api.hubapi.com/automation/v4/flows/email-campaigns \
  --header 'Authorization: Bearer <token>'

{
  "results": [
    {
      "emailCampaignId": "<string>",
      "emailContentId": "<string>",
      "flowId": "<string>"
    }
  ],
  "paging": {}
}