I am running Windows 7 Ultimate and Outlook 2013 and have an iPhone 5s. The last version of iTunes that installed the Outlook add-in was 12.0.1.26. The version released after that, and before the current version 12.1.1.4, not only did not install the Outlook add-in but also removed the ability to sync Outlook contacts and calendars to an iPhone or iPad.
The current version of iTunes, 12.1.1.4, was released to fix the sync issue as well as an issue affecting music playback in iTunes that produced skips and stutters. This version also.does not install an Outlook add-in (at least not in Outlook 2013) but Outlook contacts and calendars DO sync through this version of iTunes, at least for me.
If you cannot sync your phone and Outlook through iTunes 12.1.1.4, perhaps you should install the older version 12.0.1.26. The download is available here: http://filehippo.com/download_itunes_64/58981/