None of the many existing VCS can be used in a shared folder. I mean that if you want to use a VCS (XVC, Git, SVN, HG, Fossil, Bzr, etc.) each user must have his own "working directory". It cannot reside in a shared folder in a server.
The way to use a VCS is to put the repository in a shared location (or a specific server if the VCS support it). Then, each user make a "checkout" (or whatever it's called in that VCS) into a local and private directory. That directory is called "working directory" in most VCS and it's usually located in the user local HDD, not in a server.
The users work in their own "working directories" all the time, and do "commits", "updates", "branches", "merges", etc., to the common repository. If you're using a DVCS (distributed version control system) like Git, HG, Fossil or Bzr, then there are two repositories: the one that is shared between users and another local and private. In a DVCS there are also commands to send and fetch data from/to your local repository to/from the shared one, like Push or Pull.