UCS and Read only donain controllers RODC

I’m looking at RODC.
now according to the manual you do this:

ucr set samba4/role=RODC
univention-install univention-samba4

what is the difference between running :

ucr set samba4/role=RODC to set the mode of READ ONLY
then running “Active Directory-compatible Domain Controller” from the web front end?

if we run the command line options, nothing is shown as being installed in the web front end (really there should be some icon or something)

finally, what if we want to do some file sharing from this samba instance for users?
it seems there is no file sharing options or allocations available

Surely Read only domain functionality should not affect the ability to setup user file shares

or can we also run “Active Directory-compatible Domain Controller” from the web front end to get the file sharing , but not mess up the existing samba modes from the CLI?

and if we cannot have “shares”, why is ether a “Filesystem Quotas” icon