Hi. I tried connecting S90 directly into one of the two MacBook USB port and OS X recognized it.
It works, it’s your hub that is the problem - remove it.
Testing another brand keyboard with the Yamaha Driver is meaningless and will not work in spite of you saying it does... it is NOT using the Yamaha driver. A non-Yamaha keyboard will not use that driver. The Yamaha USB-MIDI Driver is MIDI only. MIDI ONLY. No audio or other data is transmitted via the USB port. So I’m unclear on what you are attempting to do with a hub
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If you want a suggestion on how to connect, you’ll need to tell us what you want to do and ALL the items involved. There are no documented instructions for DIY configuration - how could there be? No one is expecting anything but a straight/Direct USB connection between S90 and your computer. When you said the driver didn’t work, you initially did not mention a hub - leaving it out everything works. Suggestion: skip the hub.