Notes: I'm not sure how this particular burial site should be classified. It looks like a smaller version of the famous megalithic graves found all across Scandinavia:
"In the open, cultivated countryside, the farmers of the Stone Age built barrows or burial mounds. In the oldest barrows the burial chambers were built of wood. Later the chambers were constructed of large granite blocks. The burial mounds were monuments to ancestors and they were built in their thousands. They testify to great engineering skills, and it took the cooperation of many people to build them. In the same well organized way large enclosed gathering places were constructed where the population could forge social relations and perform collective rituals." Source: National Museum of Denmark.
I'm no expert on this, but I think it would be accurate to call this a tumulus, aka a barrow, burial mound or kurgan. "Tumulus" is a kind of catch-all term defined as "a mound of earth and stones raised over a grave or graves," according to Wikipedia. Apparently these tumuli are categorized according to their shape and they encompass a wide variety of burial types, e.g., chamber tombs and dolmens.
Judging by the size of this burial site, I'd guess that it was constructed by a relatively small group of farmers living in the valley. How they moved the stones is another question. These rocks are small compared to other sites, but they still look pretty heavy. I'm just speculating, but the farmers could've used oxen or large cattle to drag the stones into position. The auroch was domesticated in this area (I think) around 6000 years ago.