Create a Wordpress Template

I currently have a wordpress project that I'll need add some cart functionality using stripe as the payment system. I'll need to create a button like the yellow one on upper right like the [login to view URL] website. In fact we want our wordpress to function the same. When a user clicks on this button they land on a page that has these options to make a purchase; [login to view URL] When the user clicks on these they go to the shopping cart to checkout for the item but will have to login or be logged in to continue checkout. We already have a stripe account in test mode but will need to configure some type of cart to handle this. I don't want any custom development for the cart because I'm thinking that there has to be a simple plugin that allows to collect the payment through stripe. The rest should just be some configuring and design.