curl --request GET \
  --url https://api.hubapi.com/marketing/v3/campaigns/{campaignGuid} \
  --header 'Authorization: Bearer <token>'

{
  "assets": {},
  "businessUnits": [
    {
      "id": 123
    }
  ],
  "createdAt": "2023-11-07T05:31:56Z",
  "id": "<string>",
  "properties": {},
  "updatedAt": "2023-11-07T05:31:56Z"
}