A device of this type would require a driver to interface properly and fully with the computers operating system. It is likely that they did not have a driver that would work with the OS as they specifically state that it will not work with 64bit OS.
Because drivers access memory at a lower level, it became important for the driver to work with the memory as "64bit" memory addressing. That is unlike software which can be run in compatability. Somone would have to re-write the drivers to work properly with the 64bit.
The cost of such a device in these years would be much lower than it would be 15 years ago, so finding another that does have proper 64bit drivers would probably be easier than trying to stuff some driver in that may partly work.
You could downgrade the OS, or get hardware that supports the new stuff, I wouldnt even try myself.
Related: What (traditional) modems work with Windows Vista 64-bit or Windows 7 64-bit?
– sleske – 2014-01-27T08:17:24.200