Form action URL not working

I have plugin installed.. I follow instructions as shown in wordpress adfmin panel, optin plugin settings page.

I login to mailchimp> lists> signup forms> naked!

My code is
<form action="//januzaj11.us9.list-manage.com/subscribe/post?u=503b6d34daa4a8b9d95cea479&id=00b4ad9561" method="post"

So what exactly am I entering into the field in wordpress.. whatever is in between the inverted commas? I keep getting error when I test it on the front end..

https://www.ads-software.com/plugins/optin-forms/