Hey, @shalin1 .
Thanks for reaching out in our Community forum, welcome! I’m more than happy to take a look into this with you so that we can get to the bottom of it.
For context, are you trying to place a test order or process a real order through Shopify Payments? Based on the screenshot you shared, I can see that you have test mode enabled. Test mode is a feature of Shopify Payments. You can use it to test how your customers pay for their orders and to test how you and your staff process those orders. While test mode is enabled, you cannot use real credit cards to pay for orders. To enable/disable test mode please follow the guide: Testing Shopify Payments.
Please let me know if you have any questions about that. In the meantime, I’d love to hear more about what you’re hoping to achieve. From there, we can walk through the steps together to ensure that your shop is ready for launch.
Warmly,