Can't view theme when developing with Shopify CLI

Hi,

I’m knew to Shopify development so sorry if this is in the wrong place. I’ve installed Shopify CLI and created a new theme to learn theme development with but whenever I run ‘shopify theme serve’ and go to the URL it gives me it always shows me the following screen,

I’ve tried logging out of my Partner account and logging in through the stores admin and then logging in through the CLI again but no luck with that. I did try getting in touch with Shopify support but they closed the chat on me when I told them what was wrong.

Thanks for your help