This is a very crude flow chart of how a sales page COULD look. They will often look this way, but they can also go straight to a check-out page, or be initiated on a home page, or through all sorts of ways. This is likely the most common way you will use it, though.
Additionally, I have not included any downsells in this chart, but I show you how to do them in the videos below. What you will notice is there is no web store in this flow chart.
While this can be use in conjunction with a webstore like Shopify or Etsy, it is wholly different. In this model, you are guiding people through the sales process instead of letting them build their own cart.
This can be used for a special offer like on a holiday, or for a bundle you want to promote, or for a new release, or just about anything...but you cannot use it like a web store.