There is no official supported Windows 10 driver for the NI 8260.
The NI 8260 is obsolete
and therefore will not receive and further driver updates.
NI Recommends using a newer storage module with Windows 10 support, such as the PXIe-8267
However, it may be possible to get the NI 8260 to work on Windows 10. This would be an unsupported use case and has not been tested by NI. NI will not be able to assist with any issues that may arise with a Windows 10 system nor can we confirm the speed and rates of the module will be consistent on Windows 10.
To attempt to use the NI 8260 on Windows 10, follow the NI 8260 Installation guide
(created for Windows 7) in Windows 10. Specifically, the "Import Foreign Disks" step in the "Moving the NI 8260 to a Different System" section on page 15 of the manual.