You tip about circles was helpful. Thank you.
My IterLinkDX USB controller (from the RealFlight 9 bundle) is already working on MacOS with the FPVFreerider. I have to connect the USB when the first screen of the FPVFreerider simulator is already on. And then the controller is immediately recognized, it can be calibrated, and it works fine. After the first calibration no more calibration is needed, just to connect it after the first screen of the simulator is on.
I have the latest MacOS Catalina on Macbook Air notebook. It is quite a few years old already. So I switch the Graphics Quality to Low. In fact it looks about the same as High, but the simulator works as good as on my powerful Windows 10 desktop.
But, I travel with the Macbook Air, so now I can take with me the controller. (One more thing: I connect the USB controller via the usual USB hub with independent power supply, but not directly to the Macbook Air).