Twitch Login not working

I want a Social Login through Twitch. SuperSocializer is the right plugin for that, but it is not working. I putted in the right Access & Secret Key. The Website is also redirect me to Twitch to login, but after that, I will see my website in the small login window but not logged in.

One more Problem:
https://i.gyazo.com/ab3d4ccebf1a5d14ff39b90722480f30.png

How can I change for example Feb 18 to Februar 2018 or the full datum like 20. Februar 2018
Also the excerpt looks strange. Can I change that also manually?

Also here the problem with the date:
https://i.gyazo.com/3a49aa95d7c061867e666ed0aec87f22.png

I want to translate that, but in german its “Vor 6 Tagen”
So I need a prefix for “6 days ago” with “Vor”