You can control whether it uses a local or remote server by clicking on the Module Config link. Only when managing a local server will pages be available to edit configuration files and stop, start and restart the OpenLDAP server process.
If you are looking for a way to manage Unix users and groups in your LDAP database, try the LDAP Users and Groups module under the Webmin System category instead. To configure a system to fetch users and groups from a local or remote LDAP server, use the LDAP Client module, also under the System category.