Looking to the D&R web-site, I found this:
Controlling your software application
In order to be able to control a software application (i.e. play out software) with the Airence control signals (control module /
USB channel controls), one can choose one of the two available methodologies as can be seen in the figure below.
The first method is most applicable for software developers of the controlled application, who are able to integrate the Airence
USB HID Control Protocol in their application. For more information about the protocol refer to the Airence USB HID Control Protocol
chapter at the end of this document.
The second method uses a ‘mapper-application’ in between the HID messages and the controlled application and is created for
the end user. The Virtual Keyboard Mapper maps the control signals coming from the Airence mixer to standard keyboard keystrokes.
In such a way pressing a switch on the control module will lead to a customized keystroke which controls a specific function
inside the controlled application (play out software) for example.
• Method 1 (developer): - Direct access to control messages
- Full duplex: read control signals / control LED’s inside the switches
- Programming is necessary to integrate the protocol in the application
• Method 2 (end user): - Easy to use (No programming for integration in application needed)
- Half duplex: read control signals
- Quick started using the Virtual Keyboard Mapper features
With ProppFrexx you can use 'Method 2' - just like the application shipped with D&R is doing

Meaning when pressing one of the D&R switches it sends a custom definable keyboard event to the PC.
As ProppFrexx also has a freely definable Hotkey mapping feature - it looks, like that mixer and PF can easily talk to each other.