The Advanced Auto Gatherer can collect harvested crops in a 10x10 area around it. Its smaller variant the Basic Auto Gatherer only grabs 5x5.
The machine stores the crops in stacks of 40 (full box) ready for pickup. The boxes are then moved by Farmer or prisoners (prison labour) into storage or export depending on what is configured in the logistics menu.
It activates every six game hours automatically and hoovers up all the picked vegetables/crops in the farming field or vegetable allotment.