Clearly concepts of free will, mind (or consciousness), human-like AI are closely related.
I think mind could be explained as mental machinery/tools selected/manipulated by free will (if exists).
But free will really exists or it is just an illusion?
I think creating human-like AI requires creating a mind and creating a mind requires creating free will.
But I don't think randomness coming from quantum mechanics and/or determinism coming from relativity can really explain free will (assuming it really exists).
I think proving free will exists maybe impossible but disproving it is definitely possible.
If we can create a human-like AI someday (that passes Turing test and all similar tests we can think of)
(whether by keep advancing today's AI systems (bottom-up approach) or analyzing a human brain and creating a computer simulation of it (top-down approach))
that would definitely disprove free will (by showing it is just an illusion).
But if that never happens and somehow becomes clear that it never will be no matter how advanced science and technology get,
I think only then we could conclude free will must really exists.
(But then it would also mean free will is created by something beyond the laws of physics of our universe.)