first off, I don’t have a b1 silent piano or a mac- but I looked at the website manual for it (page 31) - and it seems fairly straight forward so i’ll give this a shot.
It looks like your piano driver is the same as the generic yamaha driver we get to use for the UR824. interesting.
In any case, with your driver installed and your piano plugged into your computer via usb. Fire up your DAW which I’m going to assume is cubase.
in cubase go top menu Studio → Studio Setup. from the list on the left click on VST audio system and at the top on the right under ASIO driver select “Yamaha Steinberg USB ASIO” - i think this might have been the step you were missing, and then you went looking for midi inputs and couldn’t find them (because cubase wasn’t using the driver at the time).
Next on the list to the left hit your midi port setup. I won’t be able to tell you what your midi ports will be called (because I don’t have a b1 silent piano) but in the list on the right you should now (that cubase is using the right asio driver) be able to see the midi ports associated with your b1 silent piano. I use a motu midi express - so I see a list like Express 128 port 1 - 8 etc. activate the ports you want to use and deactivate the others.
next you can fire up a midi track, select your silent b1 as your midi in, route it out to which ever vst instrument you want to play through and you should be good to go.
hope this helps or gives you some ideas…