Meta Box

Yes, I mean this, and it doesn't work correctly, maybe I explained myself badly...

When I set the mandatory fields with a maximum of 2 files, the system asks me for 2 files. I also tried removing the maximum file limit, but it continues to ask for 2 files.

I hope I explained myself better.

Thank you!

Solved thanks to this article
https://wordpress.stackexchange.com/questions/325659/how-to-check-if-post-has-video-or-gallery-block-in-gutenberg-blocks

if ( has_block( 'meta-box/my-block' ) ) {
   // ...
}

I said that badly.
I would like to do a check when a user registers in the form. This is why I identified this action:
do_action( 'rwmb_profile_before_save_user', $object );
but I do not know how to use this action to make a check like this:

$email = '[email protected]';
$exists = email_exists( $email );
if ( $exists ) {
    echo 'That E-mail is registered to user number ' . esc_html( $exists );
} else {
    echo 'That E-mail doesn\'t belong to any registered users on this site';
}