You leave the cottage i the same shape it was when you arrived. If you don't want to do the final cleaning you can pay an extra fee instead (1-2 nights: SEK 300, >2 nights: SEK 400) The final cleaning includes vacuum cleaning, wet drought of floors and dusting. You'll do the rest of the cleaning yourself.
You will find more information about the cottage, and some cleaning instructions, in the cottage when you arrive.
N.B. The accomodation is also available for reservation through Airbnb.