problem with auto login after redirection

Hello! I wanted to report a very strange bug
I have a page with a form for a lead magnet, which asks for a name and email, and after entering, it creates a user and redirects them to a course (which requires them to be logged in)

-Most of the time the auto-login and the subsequent redirection work fine, but for 30% of the people who enter the form, usually through a mobile device and usually through Instagram, the auto-login does not work and after being redirected to the course page it appears that they cannot enter (which makes me lose many lead magnets) What could be happening and how could I solve it?

I already disabled the cache and everything.

This is the page: https://recuerda.club/hcklr

Thanks