In short: The MIDI driver situation is a mess, but a solvable one. Stick to Mac, use a MIDI interface, or hunt down the MX driver hack. The S550 may be forgotten by Yamaha, but its sounds — and the stubborn community keeping it alive — prove it’s far from obsolete.
I understand you're looking for the MIDI driver for the keyboard. yamaha psr s550 midi driver
A: Yes, V3.1.4 includes both 32-bit and 64-bit. Ensure you download the x64 version. In short: The MIDI driver situation is a