The error image you shared with us I have checked and when I check the link that you shared with us the same error appears to me. But I notice there is no product in the cart and then the checkout page doesn’t appear if the cart is empty. So I added a product in the cart and I checked the checkout page. It appeared just fine with activating the AMP and the payment plugin.
Here is the video for a better reference:https://streamable.com/rzv2lt
Regards 8Themes Team.
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