Hank here from Shopify.
Thank you for the screenshot, however, I just want to confirm something relating to what I believe may be the issue you are seeing.
Are you attempting to access the checkout area from within your admin in the theme editor (Online Store > Themes > Customize)? The screenshot seems to look like within the editor, and this would be a known issue, as the live checkout links would not be accessible from within the editor.
However, from within the admin, you can view your online store (below), and test the checkout that way, or from going to your storefront via your store URL directly.
Let me know how you get on with this, or if you have any additional questions!
All the best,