The keyboard isn't connected directly to the VM - it's virtualized, so that's why there's no drivers.

Not sure why it doesn't work though, it should just be passed through.

It is passed through. But the trackpad is passed as a mouse and doesn’t seem to work anywhere near as smoothly as a mouse does. Its understandable that gestures can’t be configured in the guest. But It’s difficult to control the sensitivity or the scrolling rate of the trackpad consistently from either the host or guest. 

D’oh. 
you are correct, I read trackpad.

For me the Num-Block works, but as having NumLock not activated. When pressing the 8-Key, for example, the cursor goes up, 2-key, down.

But I could not figure out which key to press to set NumLock, getting the numbers instead of Cursor navigation.

With the default Fusion key mappings enabled, try using the "clear" key on the Apple keyboard to toggle NumLock.