Using multiple Stripe accounts with WooCommerce

I’m trying to add multiple Stripe accounts to WooCommerce and am following this guide:

https://www.neshable.com/how-to-use-multiple-stripe-accounts-in-one-woocommerce-install/

From my understanding, I need to create a new file called /public_html/wp-includes/class-woo-conditional-stripe-keys.php and put the provided code into that file.

I’m then stuck when it says to call new Woo_Conditional_Stripe_Keys( $publishable, $secret ) within the login to change the keys.

Please excuse my lack of knowledge and hopefully someone can help! Thank you!