Install this software on an air-gapped virtual machine (VMware Workstation Player is free). Isolate it from the corporate LAN.

Open PLCSIM, click Help > About . Look for "Version 5.4.8.0" or "Service Pack 8".

This version supports Windows 7, Windows 8.1, and Windows 10 (64-bit). Recent updates (Update 2 and later) have added support for Windows 11.