When we deploy to heroku everything works fine except the omniauth authentication.
We've been working on this issue and apparently is something related to configuring the correct accepted URLs in the facebook.
If so: What is the correct URL?
If not: What shall we do?

This is our website
So far. we've tried this URLs
afternoon-wave-75260.herokuapp.com
herokuapp.com
heroku.com
This authentication works fine in when this app is mounted locally
is out repository and the branch we are working on