I looked at the website and it appears to be just for the train.
Where do I find a schedule for the bus for Bahn?
You already can get on the Bahn page, right? Put in from: Muenchen Flug. It will offer some options, pick Muenchen Flughafen Terminal. For to: put in Prag (that's the German spelling). Pick Prag Hbf from the list. Put in a date; I used May 16, and the time as 13:00. Click search. The first connection shown should be 13:25 to 17:44, Duration = 4:19, Chg = 0, Product = Bus. For to: you can actually use Prague Hbf, Prag Hbf, or Praha hl.n. Does that work for you? What happened to PMs?