Hello LarsG
The latter is the case.
Holding the Saver Day Pass, you do not have to reserve seats, you simply board a train at your leisure. Our trains are free seating. Read more on that here:
https://community.sbb.ch/d/23170-purchased-a-sbb-6-day-1st-class-rail-card-cant-reserve-tickets/4
Please keep in mind, the Saver Day Pass needs your physical passport (no photos) upon ticket check.
The IC 8 line takes you from Zurich Airport to Visp, without change.
Kind regards,
Roland