Hi Gianfederico,
We need the following LDAP Server information in order to connect to it:

With this information we would need to setup the configuration as follows in the Users application:

Let's review this configuration.
- The LDAP URL you already had setup correctly. You may leave out the LDAP://, it works either way. Only if you need to use a Secure LDAP connection (and the server supports it) you need the prefix the LDAP URL with LDAPS://. The port 389 is already the default LDAP port so that part we can also leave out (otherwise it would be ldap.forumsys.com:389/dc=example,dc=com)
- Next up you need to setup the Distinguished Name (DN) credentials. They are already provided under Bind DN and Bind Password so we can just copy/paste the values in the Manager DN and Manager Password fields.
- Then we need to Save this configuration
- Last, we can test the configuration using a Username (uid) and Password from the LDAP directory. As you can see we need to append the Domain Components (DC) part here too just like we did for LDAP URL and Manager DN credentials.
As you can see this configuration seems to work just fine.
Hope this helped!
Regards,
Nordin