I got it fixed. I got in touch with disqus and they suggested two fixes which worked;
You cannot login with your email address so use your username.
And make sure you do not have underscore or any other funny character in your username because according disqus, it is a security issue they fixed so the underscore in my username was causing that.
So all I did was to change my username….
So change your username to something simple and sign in to install, after that you can change it to whatever…
https://disqus.com/account/ (click edit profile → account tab)
Hope it works for you