I have run this tutorial several times to check on this. As I am approaching the first stop, which is on the main line, I encounter a yellow 6 indication to show a speed reduction to 60 km/h is needed. I have tried applying the brake as soon as I see the indicator, as I pass the indicator and waiting a few seconds after passing. In all cases the train applies the brakes and brings the train to a stop. In the tutorial PZB is not active.
Well anyway, when out walking I was thinking about this and came to the conclusion that the game had to be treating this yellow 6 like a white 6, so I just ran it again and made sure I was under 60 km/h when I passed it and this time it did not stop me.
That's unusual, because even a white 6 (Zs3) shouldn't give you penalty braking for overspeed. Speed checking is done by other magnets before the signal and is never that precise. Cheers