Put the correct user, hostname and domain in. This is using example.co.uk as a domain. The capital w ensures it asks you for your password.
ldapsearch -x -h $hostname -D uid=$user,ou=people,dc=$example,dc=co,dc=uk -W
This search uses a standard user to authenticate.
You can authenticate using the main LDAP user and password; however I suggest creating a separate user with few permissions, just to make the bind.
You can find out the main LDAP password by running
zmlocalconfig -s | grep ‘ldap_’ | egrep ‘password|url’ as zimbra user on your mail server
If you really want to use the root LDAP user to bind the DN is uid=zimbra,cn=admins,cn=zimbra as seen below
The configuration below allows all zimbra users to connect to the owncloud instance using their zimbra details. Please also note that the default for Zimbra is to use unencrypted connections. This means that the bind is going across the network unencrypted. Hence not a great idea to use the root LDAP user. One can search for how to set up Zimbra to use ldaps.