From the Airport BER: Take the region train RB22, which departs every hour, to the station "Potsdam Hauptbahnhof". From there please take tram line 92 or 96 to the station "Nauener Tor". The hotel is located on the opposite side of the street. It's a 75-90 minutes trip.
You need to buy a Berlin ABC ticket. Here you can choose between a single ticket (4,00€), a day ticket (10,70€) or a ticket for a week (46,00€). Within the ticket price, you can take the train and the bus in all sectors (Berlin ABC).
Taxi From BER: it will take 40 - 50 minutes and cost around 110€.