Microphone sensitivity being too low and people not using PTT (Push to talk).
By they way, this website is not related to xPilot or VATSIM The correct website is below:
RWC connects your weather injector (ASXP in this example) to your cloud / scenery rendering software (SMP). If you just want default clouds, default sky colours and default effects then just use ASXP on its own.
Yes you need SMP to use RWC. RWC will not install without SMP installed.
I use RWC, SMP and ASXP and the skies look beautiful. Just make sure you go into ASXP Options > Simulator Depiction options > Use SkyMaxxPro depiction mode and turn it on