AD Connector: how to synchronize passwords

I am reading the AD connector manual and, in section 9.3 I see I can choose “configure ucs as part of an active directory domain” or “synchronisation of account data…”
I started with a fresh UCS installation and it never presented me that choice, and now I have again a system configured as first option.
How can I reconfigure AD connector to try password synchronization?
Is there a deep explanation of differences between two modes?

The first is like joining any Active Directory member server to a AD domain.
The second one is using an account to read (and write if configured) AD data and to synchronize LDAP objects and password data into UCS as a standalone environment.

If you selected to join an existing AD domain during the initial, then yes. If you opted to install UCS as a standalone domain and installed the AD connecter after the initial install, you would have had that choice.

Depending on how far you’ve progressed it may actually require more time and in-depth knowledge to reconfigure the mode instead of reinstalling it cleanly. It’s not impossible, but the modes are quite a bit different.

In “synchronisation of account data” mode you can even select if you want to replicate account data in both directions between AD and UCS or have it sync in only one direction, either UCS -> AD or AD -> UCS.