Feng Shui is about air circulation inside and outside. As long as it does not block the light in the house, it is okay to put the wardrobe.
But one thing to note is that the wardrobe should be connected with the clothes to be dried on the balcony. Separate it to let out moisture. If your clothes are dried, there will be no problem in this regard. Then the balcony will be more useful. You can install a tatami or the like, which is also very casual