SMH...... I see so many mistakes in tree planting some are so dumb as to be one step removed from 'That's not right side up'....
A tree needs to be the correct depth, which means the top of the root ball should level with the ground around it. Always! Too deep and water will pool around the base of tree, maybe drown it, mold the bark, but also, in winter, potentially freeze solid and choke the tree. But if you have the tree roots sitting high, all the water runs off, and they die of thirst.
The ground under the root ball should be loosened a bit first, so that roots can grow into it, ideally, you then put just a bit of water in the bottom of the hole and wait for it soak in, so that the roots have an incentive to grow out, rather than in a circle.
You want the base to be decently firm, just not compacted or rock solid. Then you back fill around the root ball and gently compress the soil so that the there are no air pockets, and the tree isn't going anywhere. Then give another gentle watering.
Depending on species you may apply growth agent to the roots before planting, but that's almost unheard of with caliper trees (the size you're looking at), You then stake the tree if its caliper size (two stakes tied to the tree to keep it nice and straight til it settles in, remove after six months to 1 year) and you may apply a collar around the base of the tree if you have issues w/rabbits or beavers (with species they like) to discourage problems.
It's not rocket science by any means.......but somehow.....