Unity3d - Failed to load 'Assets/Plugins/QCARWrapper.dll'

Question

I want to use c++ dll on unity android application. To use native dll on a android device, I learn that I should use Unity 5. I download unity5 from here. My application req

Answer 1

Go to https://unity3d.com/get-unity/update Under there, you will see ADDITIONAL DOWNLOADS Under that you will see FOR WINDOWS. Click it and choose Unity Editor (32-bit).

EDIT: I see lots of dowvotes. This was the ONLY solution when this question was asked. Unity 5 64bit just got released when this question WAS asked and this was the ONLY solution back then. This answer was changed to the current answer that was provided 5 months later when Vuforia released 64bit version of their plugin.