hi,
for this, you will need to have your jump animation to be "in place", and animate the position programatically, because the AR camera will always be different AND moving so you can't rely on pre made animation position, only the character arm and pose should be there for this case.
so, trigger your in place jump anim, and at the same time, animate your chracter gameobject to move toward a dummy game object that you have attached to the AR camera,
for this use the action "Move Towards" AND set the finish distance to 0 to always catch up during the sequence.
bye,
Jean