Alchitry Labs -> Alchitry Loader

Are you using the new Alchitry Loader bundled with Alchitry Labs? This should support winUSB or the FTDI drivers.

What shows up in the device manager?

For reference, this is what mine looks like.

The “USB Serial Converter A/B” entries are from the board as well as the “USB Serial Port (COM7)” entry.