For the Mac, I would suggest AFT over Kies, but that's just my preference. AFT works like a Finder window and offers drag and drop flexibility, much easier and faster than Kies. If you choose to use AFT it will not work with Kies installed on your Mac. To uninstall Kies, open the dmg file, and use the uninstaller to properly remove it. If after removing Kies, AFT still does not recognize your phone, reboot your Mac while the phone is still connected to your Mac. It should work then.
For Windows, you probably will need to have the Samsung drivers installed. You can either get them by installing Samsung Kies for your operating system or by separate download on the Samsung support website.