curl --request GET \
  --url https://prod-api.raisedonors.com/api/Donor/{donorId}/donor-fields \
  --header 'Authorization: <api-key>'

{
  "items": [
    {
      "id": 123,
      "customCollectionId": 123,
      "customCollectionName": "<string>",
      "customFieldId": 123,
      "customFieldName": "<string>",
      "value": "<string>",
      "entityTypeDisplayName": "<string>",
      "responseType": "<string>",
      "createdDate": "<string>"
    }
  ],
  "total": 123
}