Short Answer: It is not recommended to plant a new tree over the top of a recently removed stump. Simply plant the new tree adjacent to the stump, but keep the new planting hole at least three feet away from the stump to allow your new tree ample growing/rooting space (i.e., new trees need adequate mineral soil with good fertility and drainage for proper rooting and water/nutrient uptake).
The reason we don't want to plant new trees over the top of existing stumps in yard-like settings is rather simple: the new planting location will have limited mineral soil exposure and inadequate rooting depth for nutrient uptake and structural stability; the sawdust / mulch created from stump grinding has a high carbon to nitrogen (C:N) ratio, thus compromising nitrogen availability for the new tree; and, settling of the newly planted tree within the cavity of the recently ground stump.
Therefore, it is simply easier to find a suitable planting location adjacent to the old stump to accommodate the needs of your newly planted tree. Depending on the size of the stump, it is generally recommended to plant the new tree at least 3 feet away from the old stump.
Best of luck!