NoMachine server for Windows is for access to the physical display of the Windows host where it is installed. If what you want is to have multiple connections each to their own desktop, this is terminal services for Windows. Microsoft’s EULA is rather restrictive on that (which is why we don’t offer this functionality), unlike Linux (see https://www.nomachine.com/forums/topic/multiple-connections). Alternatively, you could virtualize the Windows desktop using a hypervisor technology (VMware, Virtualbox etc) and then install NoMachine on each of the VMs. That way your users would each have access to their own physical desktop (running on virtual machines).