Where is the Users page?

Sorry, yes.
Corrected.

On NS 7a3, after first login, you don’t have access at Management → Users and groups from UI.

If you add some modules that requires to create users, all dependencies will be added.

In your case, if you check Administration → Software center → Installed, you will find there “Account provider: OpenLDAP” module if I’m not wrong.

I wrote about this here:

NethServer 7.2 alpha 3 - "First Blood" - #4 by GG_jr

Is Alpha version.
I think all things will be fixed at the final version or even at RC1.

BR,
Gabriel