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Ah, I forgot to tell you the name of the games, my bad. The name is Mental from No Limit. I edit my post so all of you can see the name 
I tried both, playing normal spins and buying spins. But I do not get a nice result. It is rarely I play 300+ because usually, I play for just 100+ or 200+ spins. But reaching the bonus will depend on my luck.
No problem as I said I already recognized the screenshot, I played Mental a lot too or rather, a lot in my level, which is probably close a thousand spins
Never bought spins, I just play as regular, but I have to say 100 and 200+ spins in 1 session is not going to get you a lot of places with high volatility slots
Luck of course!!