In reply to lost1977:
How many people are you talking about? Also how much data?
Simplest approach would be to share an account, problem with that is you dont know who made the last updates etc. Advantage is it would probably be free.
Dropbox/Box/Google drive are all options.
Set up an account and then share the user name/password (personally i would sync it to another personal storage account as well in case some muppet accidently deletes it).
Could probably be done free.
Beyond that you start getting into proper version control territory where the price goes up a lot.