To enable sign in with Twitter on the Portal you need to get your API Key and Secret from Twitter. Follow the 3 steps to getting setup:
Step 1: Go to https://apps.twitter.com/app/new
Sign in with your Twitter details and create a new app, fill in the details as directed and in the Callback Url enter:
'http://yourportalname.member.site or your vanity URL.
Check to agree to the Developer Agreement & click to create the app
Step 2: Once your App is created go to the Keys and Access Tokens to copy the Consumer API Key and the Consumer Secret API Key:
Step 3: Paste these Keys into your Portal Setup in Operate:
Your Name > Settings > General > Portal > Operate and scroll to the Social Media section
Click on Save.
NOTE: Only contacts who have filled in their Twitter name in their Portal Profile and are using the same email address for both accounts, will be able to sign in using Twitter.
If you are struggling to sign in to the Portal with Twitter, it is probably because you have not put your Twitter username in your Profile.
Login to Portal with your email and password, edit your Profile and add your Twitter username.
Then log out and try signing in with Twitter again.