See the forum post here: https://forum.mendix.com/link/questions/96009
Strange though that that widget can not be found in the appstore anymorre. But the project still works and shows that it is working. I would file a support request to find out what happened with the widget.
That 3D visualization widget is part of the Siemens private app store and not available in the public appstore (anymore). I don't know the details surrounding it, but it's a commercial product that is complemented by this widget.
Other than that I don't know any current publicly available widget that does 3D model viewing.