Why Calendar is not showing on Edge browser?
simple answer. Don’t waist your time trying to get an unsupported browser working with ERPNext. Firefox or Chromium, Chrome, Brave are working fine and are available for anybody
Agree with @vrms
But note that MS announced that Edge will be using Chromium as its base and thus at some point soon effectively it will use the Chromium engine to render webpages and hence compatibility should be very much the same as using Chrome/Chromium