NI RIO 2.0 is required by the NI 5640R.
NI RIO 2.0 is included in the latest versions of the NI 5640R installer. The instructions that Anuj posted say to unselect the option to install NI RIO as part of the LabVIEW FPGA installation because the NI 5640R installer will automatically install it.
If you already have it installed, the NI 5640R installer should see that it is installed already, and take that into account when installing the files to support the NI 5640R.