Solution
The configuration of the synchronization between Axigen and Active Directory is described in the KB article available at the link: https://www.axigen.com/kb/show/269
The KB article uses an administrative Active Directory account in the configuration of the LDAP connector used for the synchronization. If you wish to synchronize the accounts from Active Directory to Axigen, and not from Axigen to Active Directory, it is possible to use a non administrative AD account in the LDAP connector.
To be able to perform the synchronization, the Active Directory account configured in the LDAP connector needs the DirSync control, or the Replicating Directory Changes permission.
Enabling this permission for the account is described in the article available at the link: https://support.microsoft.com/en-us/kb/303972
You can find a description of the DirSync control in the article available at: https://blogs.technet.microsoft.com/isrpfeplat/2010/09/19/using-the-dirsync-control/