Hello! I'm currently trying to use that same library with my Arduino Nano. Just to ask, where did you connect your Arduino? I split the wires behind the middle radio screen and connected it there (a wire with yellow dots and a brown ground wire). I used the circuit mentioned in the library readme. It uses a resistor voltage divider to get the high-signal to max 5 volts. That is not of course a best option for any faster signal but I suppose it should still work. I'm not getting any responses with those library examples on my E39 BMW. It is hard to see what's happening there without any additional serial connection. I was hoping to get those examples working at least so I could then tweak the library and the code.
It seems that you got it working at least to some extent .