I'm trying to do a POST request to my API when a user is created. I've installed Code snippets and added the following:

add_action('user_register','my_function');

function my_function($user_id){
    echo("Code has been run.");
    echo("<script>console.log('test')");
}

Now, when I register a new user, nothing is echoed. The snippet is set to "Run snippet everywhere".

I hope I've been specific enough.