Thanks for sharing. I too cannot do a two finger zoom on your map and I have a Dell Laptop with Windows 10 64-bit computer.
I did check Google Maps, ArcGIS Web map, and Custom hosted WAB application and on all of those, I could do two finger zoom.
That may narrow it down to be your application. Can you do two finger zoom on many other applications (such as google maps, arcgis web maps, etc.)? See if we can narrow down where the issue is and especially try your arcgis online web map for the map your application is using and see if that works for two finger zoom.