The modelling looks very good and clean. From recently using Maxwell I can advise that in order to successfully render interiors, it is necessary to alter the physical camera settings (I made the classic mistake of increasing the light intensity to compensate for a dark render).

To me the render looks a bit dark, so change the ISO settings of the camera "film" to a higher value. If it is currently 100, try 400 and then 800. This mimicks the use of settings on a real world camera within the renderer.

Enjoy 😄