In order to pass form submissions from an external, non-HubSpot form into HubSpot using the Forms API, you will need to pass the internal value associated with each contact property option.
So if you are trying to pass a value for HubSpot Owner, you must use the ID number string that you’d see if you viewed the property options for the HubSpot Owner property.
To find these internal values in HubSpot:
- Navigate to Contacts > Contacts Settings.
- Search and view the HubSpot Owner property > click Edit options > Look in the Internal Value column to see the ID number for your owners.