I think most USB-enabled MIDI controllers and keyboards these days are designed to work with your computer's default drivers, so in theory you shouldn't need to install a driver.
But many companies do make drivers for their controllers and keyboards just in case one is needed. I have an M-Audio controller myself, and I know that M-Audio does have drivers available, because I usually install the driver even if it isn't absolutely required:
M-Audio (m-audio.com)
EDIT: Note that the Keystation Pro 88 is listed under the "Legacy" product series on that page. There seem to be no drivers available for any specific Windows versions beyond Windows 7 (64-bit) SP1, assuming you have a 64-bit version of Windows, but I did only a quick cursory search.