I updated the previous post Revit 2015 - Update Release 5 to include the specific download links for both Revit 2015 and Revit 2015 R2 users. There is a separate installer for each version of Revit 2015.
Also, for reference, I wanted to list the build numbers Revit reports after installing the noted update:
Revit 2015 - UR4 - 20140903_1530
Revit 2015 - UR5 - 20141119_1515
Revit 2015 R2 - 20140905_0730
Revit 2015 R2 - UR5 - 20141119_0715