Oldhand is right with that statement,generally it's not encouraged to feed birds unless it is really very cold and snow covers everything up!
Birdfeeder on your balcony /patio shouldn't be problem at all,place it so that the neighbors won't get the pooh or at least not all of it,to ask the directly concerned neighbors would be a good idea too..
As for a birdfeeder on a pole in the garden you need the Ok from the landlord or renting agency.
Please try to get birdfood that contains no millet ( Hirse) grains!Once this spreads through the lawn it's a nightmare to get rid of and it's leaves can be very sharp and cut childrens feet