Here are the pin-outs from the Audi OEM cable to the H/U.
This is a view looking at the female socket.
Pin 11 = CH-DATA
Pin 9 = CH CLK
Pin 13 = R-DATA
On the diagram here, the L- and R- should be reversed. It's no big deal, as the are common grounded together anyway.
BTW-pins 6, 18 and 12 are not used.