A quick web search shows that there is at least two LDAP plugins for WP:
It appears only the first is actively maintained.
A quick glance at the feature list … it appears to me that when a user logs in via their LDAP creds, a WP User is created even though the LDAP Server is utilized for authentication. I have no experience with this plugin so I do not know if that is optional or not, but, if you wish to grant the ability for the logging in user to be able to add and maintain a directory entry, you will have to configure the LDAP plugin to create a user and map it the Subscriber role.
Additionally, you will need, at minimum, the Link extension. This is the Connections addon which allows a WP User to add and maintain a directory entry.
If it an absolute requirement that there be no WP Users created, sorry, but Connections will not be able to meet this requirement.
Hope this helps, let me know.