This gives the same instructions for growing sweet potatoes and normal potatoes.But that method will not work for sweet potatoes, they’re very different from normal potatoes. To propagate sweet potatoes you need to sprout slips from them and then plant those. So half bury the sweet potatoes side ways in some potting mix and wait for sprouts with roots to form on it, twisting those off with roots intacked and growing those. This can also be done by suspending the sweet potato half way in a jar of water with some toothpicks, root end down. Then the sprouts can be planted outside ~3 weeks after the last soil frost.
Sweet potatoes are a completely different family of plants from sweet potatoes, being marigolds rather than nightshades, they don’t bud and spread the same way potatoes do, forming one singular root rather than multiple budding roots.