How to enable register with google?

Today I purchased renewed license and upgrade to Woltlab 5.5. I created a google auth, have the Client ID and Secret set up...

In my site, now it's possible to log in with google, but not to register with google. How do I enable google option to appear at the index.php?register page?

Thank you. But I have done all of that already. I have an auth properly setup in my google account, I have the redirect set, I have client ID and secret registered in the ACP. Still, no "register with google" appears on my forum.

When I am on the "login" page, I can see the google button:

But clicking on it and choosing a google account, will become a 403 Forbidden error.

When I am on the "registration" page, there is no google button:

Registration - Carnivore Town

I would like to solve this issue before I begin inviting people to join the forum.

Quote from SoftCreatR

That is correct. It's not supposed to be there.

Okay. I accept your answer, that it's not intended to be there.

Is there any plan for it there in the future?

Thank you, I'll do it that way.