You need to install SourceAnywhere for VSS Server for SourceAnywhere for VSS Client to talk to VSS databases. The client/server architecture eliminates the need to expose the file system of VSS database to remote users and enhance the security.
It's recommended that you install SourceAnyhwere for VSS Server on the VSS Server machine for better performance. However, you can install SourceAnywhere for VSS Server in the same LAN with VSS Server. Make sure the network between the two servers is fast.