When arraving at the trainstation you just need to walk cross the street to find where you buy tickets and traveling cards for the local transportationssystem.

The airport bus is a convenient and good value service back to the city centre - but the buses only accept pre-paid tickets or credit cards. To get on the bus quicker buy your ticket beforehand if possible - available at the shop at the airport, or 2 for 1 tickets with Gothenburg pass, which you can purchase there or purchase online. The Gothenburg pass then allows you unlimited travel on public transport as well as entries into attractions in town