The maximum version of iOS for the iPhone 4 is iOS 7.1.2. So, you won't have the full feature set or functionality of newer iOS versions, like iCloud Photo Library. You should be able to use iCloud Photo Stream however, to sync photos taken with the iPhone to the Mac via Wi-Fi.
-I assume you have an iCloud account?
-What version of OS X is the Mac Pro (or is it a MacBook Pro) running?