I doubt that this code will help too much, it’s 3 years old.
Many things may have changed in this context by now which you may need to fiddle a lot.
On 2017 we decided against the official implementation ( add auth0 authentication by muhammadn · Pull Request #1435 · zammad/zammad · GitHub ).
Not quite sure what you mean, but Zammad allows you to add addons if needed…?
This thread should help you with that: