It obviously isnt being used. Id say check it out if you like it leave a note on it offering to buy it. If you dont get a response then talk to the landlord/manager of the complex and talk to them about how long its been there if its been awhile you might be able to talk them into letting you have it. I did this once and scored a nice fuji sagres road bike for free cept the prcie of paper that I used leaving notes at the doors
of folks around the place.