AltspaceVR is also available for Mac / Windows!
AltspaceVR is available for multiple VR devices but also has a 2D App for Windows/MacRead here on "how to get started on AltspaceVR win/mac/vr".
Should you not have a Win or Mac, you could consider Virtualbox or a cloud computer for the duration of the event.
Alternatively you can watch the livestream, then registration is not required.
It will be more fun to join in as you can only interact with fellow attendees through the AltspaceVR software, which is possible on win/mac/vr.