No expert here, and I have killed my fair share of young appletrees. Just sayin.
It is not unusual for a new transplant to wilt ~ the whole process is fairly traumatic for the tree, and can take some time to recover. In the meantime, make sure it is getting at least an inch of water per week, and you may want to put 2 - 3” of mulch around it.
Good luck, and keep us updated!
“All good things are wild, and free.” Henry David Thoreau
You don't say where you are, or your USDA zone. It could help! For example, I see black ground covering, and if you live where it's very hot, that might be raising the temperature a bit. But I agree, new transplants can wilt due to the stress of the changes.