Error Processing checkout

I have added this reCAPTCHA on WooCommerce checkout page and customer unable to process order.

Here is the WooCommerce log error.

2023-10-31T14:09:04+00:00 CRITICAL Uncaught Error: Call to a member function add() on string in /home/european/public_html/wp-content/plugins/advanced-google-recaptcha/libs/functions.php:354

The page I need help with: [log in to see the link]