Official comment
Which OS are you running? If you're using High Sierra (10.13), you need to make sure you actually installed the drivers by following these instructions:
1) Install the drivers
2) Disable the driver security
3) Install the drivers again right away
Even if you already have the drivers installed once, you need to run the installer again in order for the security prompt to become available (it stays active for 30 mins).
Chances are that's why your headphone output isn't working either; the audio device isn't properly configured because the drivers aren't loaded.