I think you missed some important aspects that are key to the concept. When breaking it down, you can could go element by element breaking from large to small.
Starting with the room itself, you can observe that the concept artist used several trims to break up large surfaces. This not only gives more visual variance, but a better sense of scale and perspective too.
An big part of the final result is lighting (interacts with materials, models scene, defines mood). In your case, it would be nice to have another light source than just the candle. The lighting situation in the concept is very even to show all elements, but you could prototype different lighting situation using windows depicted in the concept (don't forget indirect lighting - either bake it or fake it).
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When breaking it down, you can could go element by element breaking from large to small.
Starting with the room itself, you can observe that the concept artist used several trims to break up large surfaces.
This not only gives more visual variance, but a better sense of scale and perspective too.
An big part of the final result is lighting (interacts with materials, models scene, defines mood).
In your case, it would be nice to have another light source than just the candle.
The lighting situation in the concept is very even to show all elements, but you could prototype different lighting situation using windows depicted in the concept (don't forget indirect lighting - either bake it or fake it).
Much success