Why are Shopify newsletter subscribers not automatically syncing with Klaviyo newsletter list?

Hi @chaitra, thanks for being a part of the Klaviyo Community forum and sharing this experience.

Can you provide any additional details on what you have already tried? I know you have mentioned looking at other Community posts regarding this subject, but based on what you have shared, I feel like there are some threads that might be able to provide some more clarity to your experience. If you have a free account, you may be running into a Double Opt In issue, similar to the OP of this question: 

In particular, there’s a comment in that thread from @ksanfelipe that further explains the issue you might be running into: 

Are you using a 3rd party Shopify theme?

If you are using a Shopify 3rd party theme, your theme's default signup forms must also apply the Newsletter tag to new subscribers in order for Klaviyo to automatically sync these subscribers to a Klaviyo list. Contact your theme developer, or if you're comfortable editing your theme's source code, add the following hidden input tag to your form's input group:
<input type="hidden" name="contact[tags]" value="newsletter">

Another post that can also be useful to look over is this one answered by @retention, who goes into a lot of detail on the Double Opt In process and how it works with Shopify. 

Thanks, 
-Cass.