curl --request GET \
  --url https://crm.universal.rollout.com/api/customFields \
  --header 'Authorization: Bearer <token>' \
  --header 'X-Rollout-Credential-Id: <api-key>'

{
  "_metadata": {
    "collection": "<string>",
    "offset": 123,
    "limit": 123,
    "total": 123,
    "next": "<string>",
    "nextLink": "<string>"
  },
  "customfields": [
    {
      "type": "<string>",
      "id": "<string>",
      "label": "<string>",
      "name": "<string>",
      "originalIds": {},
      "original": {}
    }
  ]
}