For Windows clients, shares with permissions and for roaming profiles you need the AD account provider. Nethserver uses samba 4 which provides a DC instead of a PDC (older samba). Here is some info about the difference of PDC and DC.
http://docs.nethserver.org/en/v7/accounts.html#account-providers
Roaming profiles are not supported but there are some instructions:
If you installed the account provider, you are ready. No more additional modules needed as you already installed the file server module.
Win 7 clients should just work.
EDIT:
I don’t know it nethserver-dc works on this arm release, on the raspberry image it doesn’t.