@entropik This is really a better question for the HubSpot plugin, as the solution shouldn’t be specific to the Chaplin theme.
You don’t need to create a Child Theme to do this unless you wanted specifically to include the necessary code in a theme functions.php
file. Instead, I would recommend using a custom plugin that’s just the following:
<?php
/*
Plugin Name: HubSpot Custom Footer Code
Version: 1.0
*/
add_action( 'wp_footer', 'wp13354262_hubspot_code' );
function wp13354262_hubspot_code() {
?>
<!-- your custom code goes here -->
<?php
}
HOWEVER, I’m very surprised that the plugin couldn’t output the necessary code in the exact same way, so like I said, I’d request support on the plugin’s forum.