Select the field that represent the user that sold the policy. If the email of the user is not available you have to find the ID of the user.
Important: If an ID is used instead of an email you have to map the user in SalesScreen. You can find information on how to do that on [this link](https://help.salesscreen.wiki/en/articles/510350-how-do-i-map-salesscreen-users-to-external-users)