What does your contact person do?
The field "Contact person" is an internal field and generally contains the user that created the relevant data record. If you set up a contact, for example, the user you logged in with during the setup process is always entered as the contact person.
Reference is also made to the contact person for user rights, especially for the user right "just own". Consult the report "Define user rights" for more information on user rights.
It is not necessary to set up a user for the contact person, however. These can also be assigned to contact persons that do not have a bexio user. Consult the report "Set up contact person without login" for information on how to set up these special contact persons without logging in.
You can also set up contact persons for client contacts. Consult the report "Administer contacts correctly" for precise information on how this works.