How do I enable Touch ID login on iOS?

• Once you've opted to use Touch ID to login, there will be a tick box under the login button on the username screen.
• Input your username and password as usual.
• Input the last four digits of your SSN and zip code as usual.
• A pop-up will appear requesting a valid fingerprint.
• Once you've done that, you're in! From here on out, you can use your fingerprint to login to the app.
  
  Note: You will still need to enter the last four digits of your SSN and zip code upon login for security.

How do I disable Touch ID login on iOS?

In order to disable Touch ID and revert back to the standard login process, all you have to do is cancel the Touch ID request and you'll be returned to the traditional login screen.