Hi,
as I don't have a Yamaha PSR-A5000 yet (I'll better check the online stores), I think my instructions could be vague.
First of all incert the voice guide folder into a usb drive, then connect it. I think you will need visual assistance to install it or not? But once installed it's enabled by default.
The 6 kb or something file I think is the gide for using it.