For the public contacts to be in sync with the personal contacts of all users it is VITAL that one of the owners of the public contacts folder makes at least one contact in their personal contacts while the TeamContacts program is monitoring their personal contacts folder.

The TeamContacts program will add a few fields to the public contacts folder that it needs to keep contacts in sync. But it can only do that if it is used at least once by someone who has owner permissions.

Be aware that when an Exchange server administrator changes Exchange server permissions so you become owner, those changes can take a long time to become effective. It might even be needed to restart the exchange server directory service for the permission change to become effective.