FTDI really opened the door for easy Arduino access. Marvelous tech!
But, as with all open source, the ChiComs will jump on it like a pack of ravenous weasels. So, when they started cranking out a 6 PACK OF NANOS for $10, they put a knockoff FTDI chip on the USB which is incompat with Arduino IDE. You have to go get their USB driver, which may or may not be hitchhiker laden.