What version of Visual Studio are used for the driver examples?

This depends on the used RTX version and each example contains one or more Visual Studio project files for different versions of RTX and Visual Studio.
If the version of your Visual Studio is not included, create a new VS project and add the source and header files to the newly created project.

IntervalZero discontinues support for outdated Visual Studio versions with each new release of RTX.

Please refer to the RTX/RTX64 documents given by IntervalZero:
http://intervalzero.com/assets/RTX2012/OSCompatMatrixRTX.pdf
and
http://intervalzero.com/assets/RTX642014/RTX64OSCompatibilityMatrix.pdf
for a complete overview!