Where to download Once the Store World is yours you can either download it through your purchase history or directly from the world page in the Store. It does not matter how you bought the world, this is how you can re-download it. You do need the latest game version to download items from the Store so make sure you're fully updated.
This guide from crinrict may be useful to you. Sim Worlds are available for download from EA, not Origin. Check and see if you're doing this correctly.
