Original Codebase can be found here: https://github.com/the-road-to-react-with-firebase/react-firebase-authentication

react-firebase-authentication

built using: https://www.robinwieruch.de/complete-firebase-authentication-react-tutorial/

pro tip: get the app working without the database first.

most useful links:

twitter: https://www.robinwieruch.de/firebase-facebook-login/

set callback url in: app -> yourApp -> AppDetails -> edit: 
only one callback url can be used. make a new app for another callback url.
 
make sure to perform this step: 
app -> yourApp -> Permissions -> edit: 

Access permission
Read-only
Additional permissions
Request email address

On twitter make a privacy policy doc before heading over there as it is required. You can give a bogus site but not for a prolonged period.

facebook: https://www.robinwieruch.de/firebase-twitter-login/

after creating an app look for products, Facebook Login.
That is where you will input redirect URI's.
More than one can be input at once.

Additional troubleshooting:

consider, set process.env.REACT_APP_CONFIRMATION_EMAIL_REDIRECT to window.location.href.

Time for the database.

Setup a realtime database on firebase. change the first to have table user.