After depositing 30 euros, I accepted the 50x requirement. However when I looked at the turnover, they moved the goal posts and the system showed that I needed to do a 90x turnover of the bonus. Moreover, now the details of the 300% first deposit bonus now state that it is 90x since they changed it from 50x to 90x to cover their scamming.
Original 50x:
https://i.imgur.com/dhAxQXZ.png

Now 90x:https://nitrowinner.com/en/promotions/promotion/121
https://i.imgur.com/GKNSeI2.png

If you accepted the 50x 300% first deposit bonus, you get the fun surprise that the system requires a 90x turnover. But of course they had to change the terms of the bonus section to 90x since I had pointed out the error in my earlier post. I received an e-mail where they state that it is 90x (i.e. they won't honor their 50x obligation).