Login WP – Connect single field to an external api

I apologize but I only now have a way to post my solution, maybe it can be useful to someone.

Here is my solution to the problem:

$new_user_id = wp_insert_user($userdata);
$value = json_decode($response['body'], true)['Id'];
// get value from response you want to set
update_field('field_60084ad3970a8', $value, 'user_'.$new_user_id);