In terms of weight and deflection, there’s almost no issue with storing a fridge on a floor. We design buildings with strong factors of safety regarding weight (especially ‘live’ loads like appliances and people) – so there should be no problem. For peace of mind, place it next to a wall for the most efficient stress redistribution. On the other hand, a fridge CAN harm your wooden or vinyl floor by scratching it. If you need to move a fridge, try to lift it entirely or move it on top of towels.