You can ask HAI for clarification on what they meant with this comparison chart, but I could think of one way that will make the statement technically correct, but not very useful in your situation, like connecting 64 thermostats with 1-2 remote sensors on each. If you really want so many HAI temp sensors, you could consider either having 2 HAI controllers with some software in between for coordinating, or use the relays and periodically switch a zone between 2 sensors. I am not sure how the relay will affect the sensors signal, but you can calibrate it empirically.
Also, if your application permits, consider using 14A00 sensors that can be connected to any zone.