Cant connect with twitter from Ipad air 2

I cant save my progress in this game. Because cant connect with twitter. After I press "Authorize" getting black screen. I am planning to buy some song packs but I am afraid that I loss my purchased songs, because I cant log in. Fix please.

Otherwise, Thank you so much for this awesome rhythm game. sure 5 stars! Please add more beautiful songs :)

Tarnmaster about osu!stream