Ok - a little bit more help here

On Monday 9/21 - a bunch of us (15+ most likely) are going Munich to Salzburg for the day (returning the same day for most of us). I believe that the Bavaria Regional ticket (28 Euros for up to 5 people for travel on one day) is applicable to most (if not all) trains between Munich & Salzburg? These tickets don't have to be bought until the time of departure at the station (ticket booth or automated kiosk?)?
Thanks in advance.