at the very least, you need webviewextras2 (not version 1.42). there is a permissions event you need to consume. that's your webview popup.
and although the camera is controlled by the webview in this case, you will probably need the usual camera and audio runtime permissions for the app. that's another popup. it comes first. no harm done if you add these, and they actually weren't needed. (you're welcome to try without them. as famous french programmer blaise pascal once commented - in a different context - the benefits outweigh the liabilities.)
hopefully, you are familar with both these facets. permissions for the app are the easiest to deal with: declarations in the manifest and 2 quick dialogs in the app to grant the permissions. many, many examples available (use the search box above). working with webviewextras2 will require a little study of that library. worth the effort.
whether or not your app ends up doing what you want it to do will have nothing to do with the issues at hand. they're pretty straightforward; grant the permissions, and you're good to go.