cFP has been discontinued more than 10 years ago. You need to try to find a NI-Fieldpoint driver installation. However there is no way to develop the control software for the cFP controller in anything than LabVIEW Realtime.
As to accessing the Fieldpoint hardware from something else than LabVIEW, that is also going to be tricky.
The latest download for NI Fieldpoint is version 15.5 from here: https://www.ni.com/en/support/downloads/drivers/download.ni-fieldpoint.html.
15.0 was the first to officially support Windows 10 but never Windows 11. While it may be installable under Windows 10 there may be issues under more recent versions of Windows 10.
But I don't think there was ever official support for calling this through .Net. Theoretically the NI Fieldpoint API is a DLL, so to simply access the controller and read some data from a module should be possible. But that DLL is a native Win32 DLL and you need to have an Interop interface to it, which I doubt would be available from NI. There is no documentation about accessing this from anything but LabVIEW.