You need to have the latest Firmware installed on the 
goggles.
To update the 
Goggles firmware, download the version of DJI Assistant from the 
Goggles Downloads area of the DJI website,
(not just any DJI download area, the 
Goggles Downloads area).
Unfortunately, my sense is that not all versions of DJI Assistant are the same and there is not an obvious indication of this. 
Some Assistant versions are for the Mavic aircraft, some for RE 
Goggles and some for regular 
Goggles.
Connect the 
goggles (only) to your computer and update the 
goggles firmware with DJI Assistant.
After updating, have the RC controller and Mavic Zoom powered up and connected. Power up the 
Goggles.
Follow the DJI website for general instructions on connecting to your Mavic.
An important item is in the 
Goggles Settings under the Link menu, where you select "
Mavic 2" as the type device to connect to.
Good Luck!