I just installed VS 2015, the installation was finish (after some fail time caused by the slow network, I run setup again).
I create a project as Adroid > A
There is actually a connection between running Visual Studio as administrator and setting the registry path.
I followed the instructions here but it only worked after running VS as admin because my Android SDK path is in "C:\Program Files (x86)". So in order to add or change files there you need admin rights. Alternatively you can change the permissions of the "Android" folder so that the group "Users" as full access. This worked for me as well.
Or you make sure you don't even install the Android SDK in "C:\Program Files (x86)".
By the way I found that restarting VS, or even the Emulator again wasn't necessary after I added the registry key. It picks it up when it needs to.