Greetings from Carinthia(Asutria)
It sad that you´re not allowed to keep a dog in your flat, you should look out for a new one- I, myself can´t imagine living without my dog I must say. I´ve a flat, too but no one ever did complain about my dog(s) even though it´s not allowed, too. But some of the people here have cat´s /Dogs and nobody cares.
I´m sure that Cyrus LOVES every minute when you are with him and that he wishes you to adopt him and nobody else. It´s great what you do and even though you can´t keep him now, please keep walking him.
I hope you will find a solution for this problem,