Create Shopping Cart Summary Page

In the top navigation bar, Go to Pages and then press "Create a Page"  (You can select the branding page template for your new page while creating it but, you can also change it anytime afterwards if needed). 
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Once, the page is created, you can drag the shopping cart summary widget from the right hand side widgets list under ECommerce

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Once, the widget has been added to the page, you can press "Edit" to configure the link to shopping cart page and to checkout page.