Turning OFF ringer on laptop

One approach would be to go into your Zoom phone settings and under call handling, untick the Zoom phone desktop apps. That will stop any desktop OS (Win&MAC) from ringing inbound. This will only affect inbound calls. You can still make outbound calls from your MAC book. 

Open Zoom client on your PC and go to settings. Go to the Audio tab and scroll down, you will see the ringtones section. You can then select silent, which is at the bottom of the list.