If people conquer Mara can they float up while meditating?

By floating in the air, I assume you are referring to levitation and flying in the air which some groups or individuals claim to be able to do.

Hinduism, Gnosticism, Christianity, Judaism, and Buddhism all have stories of spiritual leaders displaying the power of levitation. And in Hinduism a siddhas (one who has achieved spiritual powers) have siddhi (powers) one of which is the power to levitate. Called Laghima (the ability to make the body very light), which is listed as one (1) of the eight (8) main supernatural powers in the Hindu scriptures.

Scientifically there is no evidence that levitation exists and alleged levitation events have all been explained by natural causes or exposed as hoaxes. So from the Scientific prospective, the answer is you cannot levitation while meditating,

From the prospective of the siddha or mystic, the story is different. But this is more complex and their so called supernatural powers cannot easily be proven or disproven. I say this because the manifestation of these powers is outside the reality of humanness. We are crossing over into a spiritual reality, this spiritual reality is the Atman consciousness or states of pure awareness. I use the term humanness to distinguish a state of mind that has psychological barriers blocking or limiting its perception. Atman consciousness or pure awareness is free from these limiting filters and as such enlightened siddhas or mystics can perform what seem like miracles or supernormal abilities, and they can also temporally hook normal human awareness to this Atman consciousness. As for example Jesus walks on the water to meet his disciples.

But really anyone claiming to be able to teach you to Levite through meditation is making a false claim, as you would need to experience Atman consciousness to manifest any of the eight (8) main supernatural powers, and that is something you cannot be taught, your mediation instructor can lead you towards that goal but only you can cross over into a higher state of consciousness.