Here are the settings one customer used to configure our LDAP sync tool ("Tools->LDAP user sync") to work with Kerio Connect 8:

LDAP SERVER
                Directory Type:               Other
                Hostname:                     fqdn.domain.com (IP address only works for non-SSL connections)
                Port:                             <Blank>
                Use SSL Connection:       <Checked>

 AUTHENTICATION INFO
                Username:                         <Any Kerio Account>
                Password:                           <Kerio Account Password>

SEARCH PARAMETERS
                Base DN:                        fn=ContactRoot
                Email Attributes:              mail,uid,otherMailbox,rfc822Mailbox,apple-generateduid
                Filter:                             (objectClass=inetOrgPerson)

 AUTOMATIC SYNCHRONIZATION
                Frequency of Auto-sync:    <Whatever works best for your organization>
                Email Address:                 postmaster@domain.com