How to track user registration on the site through social networks using GTM?

Question

Google Analytics

The site has user registration. Registration sequence:
1) The user enters his data or selects the social network through which he wants to register (gmail, facebook)
2) The user creates an account by entering the necessary information. One of the steps is account verification, here it is redirected to the gmail or facebook website (in the same web tab). Verifies the account and redirects back to the site.
3)User on the account page (in case of successful registration). User on the error page

When going to a third-party site and returning back, the gtm container is reinitialized.
There is no unique page confirming successful registration.
The site is implemented as a SPA.

Answer 1

https://blog.peklo.studio/how-to-set-up-tracking-i...