Start up Nokia Photo Transfer and you should be offered the update, just grab it and then restart the application:
You can find Nokia Photo Transfer for Mac here - it's not distributed via the Mac App Store, which is a touch odd but certainly not an issue. It's a free download, of course.
On Windows PCs, of course, much of this is available via MTP just by plugging a Windows Phone in via USB, but it's nice to have quick and easy captured media transfer on the Mac too. In fact, Nokia Photo Transfer also scores by telling you when images are available in both normal and full resolution (e.g. on the Lumia 1020 and 1520) and copying across both/all JPGs as a matter of course.