In order to run parallel STAR-CCM+ must be installed on each of the machines you wish to run on. On Windows machines you must also ensure that MPI is installed on each machine, and that the STAR-CCM+ installation path is the same on all the machines. On Unix machines you must ensure that you have rsh access to each machine.
At present STAR-CCM+ only supports homogeneous parallel servers so, for example, you cannot start the controller process on a Windows machine, and have the workers running on Linux boxes. The client process need not be on the same architecture as the server processes.
You must also ensure that you have the correct number and type of licenses required for a parallel server.