Aloe vera leaves cannot be propagated by simple cutting it from the plant. The leaves should have a stem tissue attached to it in order to grow roots and pups.
The only way for the leaves to have a stem tissue attached to it when cutting for propagation is to cut the trunk of the Aloe vera plant and remove the leaves in a certain way that a small part of the stem is still attached to the leaves.
After cutting the leaves, let it dry in a well lighted room but without direct sunlight for about a week before planting them in the soil.
Even though you can plant it after drying, it is better to wait for two weeks for the roots and pups to come out before planting them in the soil.
Watch the video below on how to cut the Aloe vera leaves for planting.