Cable, etc.
You will need a way to get the cable through the wall to the outside and mount an antenna, not a simple task in any building, especially an apartment. If you are already on an upper floor, just moving the scanner closer to a window might be enough. The magmount antenna you have requires a flat steel surface, something that is not common in many buildings where air and heat ducts are often aluminum. A metal baking sheet has been used by some for mounting, but it will have to be anchored in a horizontal position for best results. The cable presents other considerations. To best match the antenna cable, RG-8 would be better to avoid signal loss, and you would need BNC connectors for the cable to the radio and the cable to the antenna connector. You could use RG-58, but it will have more signal loss, especially on the higher frequencies.