The coach stop Tegel Airport is located at Terminals A and B at the access to the airport. The stop is mainly served by the coach company Flixbus. https://www.berlin.de/en/tourism/travel-information/intercity-coach-services/4402039-4510513-coach-stop-tegel-airport-txl.en.html
https://www.berlin.de/en/tourism/travel-information/intercity-coach-services/4402039-4510513-coach-stop-tegel-airport-txl.en.html