Hi there!
As far as I can tell in the two example you show (your own render and the one with more light on the balcony ceilings) everything looks and behaves as you would expect:
1) In your render the light comes from the left and is being blocked by the big red vertical structures, thus: less light on the balcony floors, and less light to be reflected upwards. If the balcony floors are in a dark materials this will affect the lighting even more. Also, you have exterior sunlight and "semi interior" light (on the balconies) in the same image, so as said before, either your exterior big light block on the left wall of the building will look okay (not overexposed) and the (semi-)interior parts will look too dark, or you set a longer exposure to make the balconies brighter, and the exterior will be overblown.
This, by the way, is a classic case of the tension between clients asking for realism on one hand, and on the other hand asking for "more light here, more reflection there" etc... when what they ask is simply not realistic. The quickest solution is not to argue and just do what the client asks, believe me
2) In the other example you show the balcony ceilings nicely lit. There is a good reason for this: look at the lowest balcony and the shadow it casts: if falls on the wall but not on the ground. This means that for the other balconies, there is also no shadow at all on the balcony floors. All balcony surfaces are lit 100% by the sun, and thus have LOT of light to bounce upwards towards the underside of the balconies. Add to this that the building is very white, so a lot of light get distributed.
My shortest advice to you:
1) If all you need is that still image in your shot, fake things by giving the balcony floors (and potentially the walls and ceiling as well) a tiny bit of emission.
2) If you don't want to do that, give the floors a colour that is as light as you can, given the design, and make sure the sun hits the floor under an angle where the most light hits the balcony floor. More sunlight on the floor = more light to bounce around.