There is several different sets of users/groups/permissions that you need to think about here. Assuming you are on a Mac.
a) There is users/groups/permissions on your local desktop (Mac).
b) There is users/groups/permissions on the DroboShare (which is running a very weak form of embedded Linux called BusyBox).
When I use smb to connect to my DroboShare and I hit command-I (get info) on a file, the Sharing & Permissions part at the bottom of the window just says “You can read and write” because I’m connected to the DroboShare as a Guest user.
There is no mapping between the users/groups on your local system and on the remote system (the DroboShare). smb on the DroboShare runs as the root user [370 root 2056 S usr/sbin/smbd -s /etc/smb.conf] so it has full write privs to any files in the mounted directory [/mnt/DroboShares/Drobo].
ssh logging into the DroboShare and setting permissions or users/groups only does it for the DroboShare, but like I said, unless you setup smb differently, it doesn’t matter because it always runs as root.
I’m not sure if the version of smb that comes on the DroboShare can be configured to do the mapping, but it is pretty easy to setup if you know what you are doing and assuming it works with that version of smb.
It is possible to configure BackMyFruitUp to do authentication and user/groups/permissions. But that is left as an exercise for the reader: http://netatalk.sourceforge.net/2.0/htmldocs/afpd.conf.5.html
That said, what Jennifer isn’t saying directly, but I will… the reality here is that the DroboShare really was never intended to be a multiuser fileserver. It really is nothing more than an $200 appliance, not a several thousand dollar file server. It is a completely underpowered server for handling multiple people connecting to it concurrently. If you want a better solution, buy a Mac Mini for cheap and connect your Drobo to that. Then just turn on File Sharing.