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