I am planning to move from Windows 10 64bit to Windows 2016 64 bit. I currently have a 2 disk array raided.
Once I boot to the new OS, what is the processes of establishing (moving) the raid to the new OS.
Technically, that's a downgrade; the new (2020) Windows Server is the latest.
The latest RST package for Windows Server 2016 can be found here: https://downloadcenter.intel.com/download/28992/Intel-Rapid-Storage-Technology-Intel-RST-User-Interface-and-Driver?wapkw=Intel%20RST%20for%20windows%20server%202016.
I would suggest that you inject the drivers (in download file f6flpy-x64.zip) during the Windows Server installation process (at the screen where you specify the system drive). Then, install the package (download file SetupRST.exe) once the Windows Server install is complete.
Hope this helps,