Using Signup API how to auto login user after successful signup

I finished this tutorial here:

So i’m using PassportJS with Auth0 to authenticate the user in NodeJS Express

To register the user I needed to create a more custom onboarding experience than the universal login so I’m using this API call which is working great.
https://auth0.com/docs/api/authentication#signup

However after the user registers I can’t figure out how to auto log them in. I know there is a /callback route but I’m not sure what parameters to pass to it.

Any ideas on how to get an auto login to happen after using the signup API?

I found this topic: Silent Auto-Login for User after Completing 'Authentication API'-Backed Custom Signup Form

Where he seems to have figured out how to do it, I can’t figure it out for NodeJS Express with PassportJS

This conversation is happening here as well, I am going to link it and close this one.