This documentation is not using the current rendering mechanism and is probably outdated. The extension maintainer should switch to the new system. Details on how to use the rendering mechanism can be found here.
The only mandatory field is the configuration name. This is only to name the records you have just created.
Please note that you may create multiple configuration records with the same (or another) LDAP server. It may then be useful to restrict a given LDAP configuration to be used to one or more domains. In case the list of associated domains is left empty, then the corresponding configuration will be valid for any domain.