On the Weebly platform, customers do not have access to the CSS/HTML for the cart and checkout page. This means that you will not be able to place the engagement or Shopper Identity Protection trustmarks directly on those page.
The floating trustmark, however, does automatically appear on your product pages, shopping cart, and checkout page when you install the McAfee SECURE app.
We do recommend that you add the engagement trustmark to your site footer. Since the footer shows up throughout your website this trustmark will also show at the bottom of the page to reassure customers that they are on a secure site.