FunnelKit (formerly WooFunnels) checkout is fully compatible with Klaviyo. You can enable the newsletter option on its checkout page in an attempt to grow your mailing list.
Let’s learn how to do it.
Click here to download the Klaviyo plugin on WordPress.

Now, upload the plugin and install it.
Go to the Fields tab in FunnelKit (formerly WooFunnels)
When creating your funnel checkout page, go to the Fields tab.

Drag and drop the field on the checkout form
To display the newsletter option, drag and drop the Klaviyo field on the checkout form.

When done, click on the Save changes button.
This is how this option will look on your checkout page:

That’s it! You have enabled the newsletter option on your checkout page.