Hi @haunguyen,

Welcome to the Community! 

It is a bit difficult to answer your question without the context of your current Klaviyo integration, but if you have followed all of the necessary steps when integrating your Klaviyo account to your website, that sign-up bar should send your subscriber data over to Klaviyo.

A great way to test this would be to input your email (or a test email you have access to) and check your Klaviyo Profiles to see if the new subscription is reflected there. If it is not recorded as a new subscription within about 10 minutes, this may be an indicator that your site is not fully integrated with your Klaviyo account. 

I will link some Help Center articles below that you can explore to help troubleshoot further if needed:

• Developer's Portal: https://developers.klaviyo.com/en
• Shopify: Guide: How to Integrate with Shopify
• Magento: Guide: How to Integrate with Magento (2.x)
• BigCommerce: Guide: How to Integrate with BigCommerce
• WooCommerce: Guide: How to Integrate with WooCommerce
• Custom: Custom Platforms & API

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Hope this helps!

-- Ashley Ismailovski