What you can do:

[1] create a folder for each of them; i.e. "Bob", "Sally", etc.

[2] turn on sharing for each folder, giving access to only the person that the folder is for -- make sure that you select "Full access"

They will each be required to create an account with my.pogoplug.com for the full access to work.

When they open the desktop app they will have a folder called "Files shared with me" and within that folder will be their named folder

When they access my.pogoplug.com they need to go through the "Shared with me" to see their stuff.

Sure, just follow what I said above and have each laptop access its own folder.