Hi @suneth2! Thanks for reaching out. These questions would be best directed to our support team. I recommend creating a ticket for our support team by following this guide:
https://help.klaviyo.com/hc/en-us/articles/115001002272-How-to-Contact-Support
Once you create the support ticket you should receive a reply shortly with troubleshooting steps and follow up questions. Please include a screenshot of the error message that you are seeing in your account in your support ticket as well.
We usually see these errors if you have a security layer on your site blocking our requests, but our support team should be able to confirm and steer you in the right direction. Thanks for getting in touch!