What to do if I can't arrive during these hours
If you don't have the opportunity to arrive on 23 August you'll find the time table and prices for the Airport coaches on this webpage:
You can buy tickets for the airport coaches online, in a vending machine or from the driver. When you enter the bus, show your airport coach ticket and ask the driver for a valid one-way ticket for the trams and buses in Gothenburg city. You will get the bus and tram ticket for free and it will allow you to travel to your accommodation.