The precursors in space and time for the outcomes of free will, agency, and free choice all of course simply exist in a quantum causal set. In a quantum causal set, however, there are many outcomes that have unknowable precursors even though those precursors do also exist in the causal set. The unknowable quantum precursors make quantum outcomes fundamentally uncertain and therefore subject to free choice as the free will of the conscious agents of our quantum reality. However, the collapse of quantum phase coherence means that some outcomes are still much more likely than other outcomes and that is the basis of the largely determinate classical reality of complexity and chaos.
The term quantum spacetime is somewhat of a misnomer since the gravity outcomes of determinate spacetime relativity are fundamentally inconsistent with the uncertain outcomes of quantum relativity. While a unidirectional and entropic time and space are objective determinate outcomes in spacetime, quantum time is reversible and quantum space allows for both superposition of simultaneous outcomes in one place as well as entanglement of simultaneous outcomes across the universe for all time.
Free will is just one of the many unconscious archetypes that are necessary precursors for the outcome of free choice. Unconscious archetypes are unknowable precursors but are still part of universe and therefore also lead to outcomes such as free choice. People tell all kinds of stories about the subjective precursors of the objective outcomes of unconscious archetypes, but there is no way to objectively measure unconscious archetypes, despite their being precursors to the outcome of free choice. The universe is very complex and our limited and finite minds cannot ever hope to know all of the complexity of even knowable determinate precursors. Therefore many very smart people will continue to argue that complexity and chaos alone are what explain free will in a determinate universe and there is no quantum uncertainty involved.
However, uncertain quantum outcomes mean that the universe is not really determinate after all and so given quantum uncertainty, even beyond complexity and chaos there are still fundamentally uncertain outcomes with unknowable precursors. The key difference between the outcomes of the determinate relativity of gravity and the uncertainty of quantum outcomes is quantum phase. It is then the collapse of precursor quantum phase coherence that defines quantum outcomes. It is only incoherent light and matter action that make up the determinate outcomes of gravity relativity while quantum light can remain indefinitely entangled with its matter action outcomes.