Some people are only just finding out about R2 now, partly because it is only available through the subscription site and you have to have a valid subscription in place to access it. Some of those folks in this position, in the meantime, have installed the Update Release 5 already, or even 6 and 7. Get ready with the sad trombones...
Per Autodesk support:
Given this scenario, you will need to uninstall and reinstall Revit 2015 if you want to install the R2 version of Revit 2015 and its subsequent updates. The reason for this is that the R2 updates, including the R2 versions of UR5, UR6 and UR7, only target Revit 2015 R2 installations. Likewise, non-R2 updates only target non-R2 installations of Revit 2015.
Will these help?
This means if you've already applied release update 5, 6 or 7 to your installation of 2015 without the R2 release in place, you'll have to start over, reinstall 2015 to get things in place correctly to apply R2 at all. This could have gone better for some, wish it were simpler.
At this point I think I'd just wait for the release of Revit 2016 which, if the past years are any indication, ought to become available mid April to early May. If your project must stay in 2015 but you really want the R2 features maybe its time to talk to Gordon at Pragmatic Praxis to see how his deployment tools can help you?
While you're working this out please let me recommend this Irish Whiskey, if you happen to enjoy a dram on occasion...