I was referring to the quickstart guide offered by auth0 for chrome extensions. Anyways, after retrying one more time, I found the problem. The quickstart guide has a typo here
https://<YOUR_EXTENSION_ID>.chromiumapps.org/auth0
I was using it to fill in my callback url BUT, the correct callback URL should be of the form
https://<YOUR_EXTENSION_ID>.chromiumapp.org/auth0
So yeah… one s
character.
As a side question, does custom authentication plays well with chrome extensions? Is it worth trying? I would like to get rid of the default popup that launchWebAuthFlow offers and make authentication feel more “integrated”