Can I download something that will let me run Casmate 9.5 on Windows 8.1 64 bit?
You can do it with a virtualization program. The most known one is VirtualBox. However, this procedure requires you to have an original installation disk of Windows XP.
Download VirtualBox: https://www.virtualbox.org/wiki/Downloads
Create a virtual machine tutorial: https://www.virtualbox.org/manual/ch01.html#gui-createvm
After all has been installed, drag and drop Casmate9.5 and you'll be able to run it properly.