Email template not working

Hi there, I have set up the Email Templates plugin as well as WP Mail SMTP, send a test email to myself and everything seems fine. When I write an email unfortunately there is no trace of the template. I have tried with webmail, gmail and apple mail. I have tried to:

Copy the templates folder into your theme , then in functions.php add the following:

add_filter(‘mailtpl/customizer_template’, function(){
return get_stylesheet_directory() . “/admin/templates/default.php”;
});

but the second line apparently has a syntax error and when I save the file the whole site is just a blank page. Can you please assist ?

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