Have a look at trainline.com. There is a coach from san sebastian donostia in the early hours of matchday at 00:50 and arrives in bilbao at 02:15. No other coaches that day before match. Nothing ventured nothing gained.I’ve been trying to get a car and driver to take us to/from Vitoria. No luck so far, so I booked one of the last car parks I could find for 90 euros. It’s cancellable so I can keep looking for alternatives.