Thinka has multiple configuration options, mostly optional, for controlling thermostats. I'll try to explain each option and try to describe how this option is available in HomeKit.
First off, the most simple version of a thermostat is one where you can only set the target temperature. To get this to work Thinka only requires two group addresses. One address for the actual temperature and one for the setpoint temperature. Use a temperature sensor when you only want to be able to read the actual temperature. This will show up in Apple's Home app as a simple temperature slider. Or use Siri:"Hey Siri, it's cold in here" "Okay, I'm warming the living room from 19°C to 20°C."
We can also let Thinka know if your KNX climate system is currently heating or not. This is done with the "Heating status" setting. When you system is heating this will show in the Home app as "Heating to X°" and the icon will turn orange.
Same goes for "Cooling status". This only applies if you KNX climate system supports cooling and it works the same as the "Heating status" above. This will show in the Home app as "Cooling to X°" and the icon will turn blue.
Some KNX climate systems require manual switching between heating and cooling and don't do this automatically. For this to work from HomeKit you can use the "Heating/cooling mode" setting. This setting shows up in HomeKit when long pressing the thermostat icon in the Home app and then go to "Mode" at the bottom of the screen. When this setting isn't used the "Mode" will be set to "Auto" and Thinka expects the KNX climate system to switch between heating and cooling automatically.
The last available setting is "Operating mode". This enables the HomeKit option to set the Thermostat to "Off" from the "Mode" menu. For most KNX climate systems this means the system is switched from "Comfort" to "Building protect" and prevents freezing or overheating the system.