Triberr has switched from a sign in proccess using an email and password, to a new method requiring you to use your Twitter account to sign in.
This change makes a lot of sense since, in order to use Triberr you do need to have a twitter account. You should be asked to connect to your twitter account via OAuth and you should be good to go.
Here’s a quick visual step by step in case you need it:
That should do it!