The free spins won't allow you to win anything. It is just a promotional tool to draw you in so you play more. Its just like how casinos will givep layers free rooms and free food so they stay longer and play. For whales they give them the most ridiculous perks and even let them fly the casino's private jet just so they bet millions.
Yes, I agree to you about that because at first I also try to spin a its 25 free spin but I did not won any of coins, so that I realize its just a promotion to play more to them and deposit.