Hi There,
Do you want to display the popup form for all the pages?
You have to setup a child theme first:
https://theme.co/apex/forum/t/setup-how-to-setup-child-themes/57
After that add this code under functions.php
file locates in your child theme:
add_action( 'wp_footer', 'print_mailchimp_popup' );
function print_mailchimp_popup(){
?>
<script type="text/javascript" src="//downloads.mailchimp.com/js/signup-forms/popup/unique-methods/embed.js" data-dojo-config="usePlainJson: true, isDebug: false"></script><script type="text/javascript">window.dojoRequire(["mojo/signup-forms/Loader"], function(L) { L.start({"baseUrl":"mc.us7.list-manage.com","uuid":"05caf4abe427a3eee8cb53990","lid":"de59be9e7a","uniqueMethods":true}) })</script>
<?php
}
Hope that helps and thank you for understanding.