Arriving from risk area (Munich)

Hi, all! I will be arriving on September 18th from Spain to make a German course and due the COVID restrictions I am supposed to either quarantine for 2 weeks ( which is a lot considering I will be staying for a Max. Of 3 months) or get tested on arrival at the airport. Has someone already done that? If so; was it easy to find the place? Smooth process? How long did it take for the results to come? In the mean time are you allowed to go to the supermarket to get food? Thanks very much to whom take the time to answer me. Best regards!!