Unity 2019.3 XR Plugin System - OculusXRPlugin dll not found on MacOS?

I'm trying to use the new XR Plugin system to develop a Quest app with the Oculus XR Plugin installed, and getting an error stating that the OculusXRPlugin dll couldn't be loaded when I try switching to play mode.

Is the XR system windows-only? Am I missing something obvious?

/edit: I should note that I'm aware I can't actually use my headset in Unity on Mac. Just trying to run it flat in play mode.