hey Melody,
Pretty sure your free-shipping popups are the problem. I added a product to the cart, and once I hit the cart page I got one popup, and then another. The problem is you can't close either of them, so you can't click Checkout. See the attached screenshot..
I was able to close the popups on other pages, just not you cart.
On a side note, if you're interested in finding out why shoppers may be adding products to their cart, but not checking out, take a look at our app Secondlayer.
Hope that helps!
