Need help with radio calibration (0 channels) pixhawk 4 mini radiolink AT9S R9DS

I have the following setup:
Flight controller: Holybro Pixhawk 4 Mini (in QAV250)
Receiver: Radiolink R9DS
Transmitter: Radiolink AT9S Pro

1.) Should I use SBus or PPM?
2.) Is my wiring correct? See pictures, I’m using PPM right now (Documentation on the web is very bad I think)

3.) Why are no channels detected? Edit: Receiver and transimtter are bound

Thanks in advance