First check whether the webcam is working or not, for this you can use any webcam test website by searching online webcam test on google.
First time when you login to https://vms.isocietymanager.com/  it will ask for camera permission in the browser.  Allow it to use came.
3. In case you missed this permission alert, you can check the permission anytime, by clicking lock button on top              left of the browser. Please make sure camera permission is given.