We are creatures and we are made of some substance. If there is one substance, then we are determined by the rules that govern that one substance. Determinism is a necessary component of any monism. God thinking reality would produce the same effect from our perspective as no-God vibrating strings bouncing around. Our seeing vibrating strings of energy bouncing would simply be our model of what occurs through god's thinking to create reality if idealism were true.
We must end up with exactly the same perspective on philosophical quandries -- human free will, etc. -- with idealism as with any monism. There is no free lunch. We cannot derive magic out of idealism any more than we could out of neutral monism or materialism. The reason behind this is because what we call mechanism is just the means of interaction of the single substance, whatever its ultimate nature. It has to look exactly the same to us no matter what it actually *is*.
Every attempt to appeal to 'magic' (a fundamentally unexplainable interaction, such as a true miracle) means that two substances are entertained. So, for instance, if we wanted to appeal to libertarian human free will in idealism, that would require some form of different substance than God's mind or we would see an entirely different type of world. If the original substance is god's mind and everything else is action within god's mind (reality) it necessarily follows that god's thoughts function in exactly the same way that material substance function. Determinism necessarily holds. Belief that every individual is a truly independently free entity not determined by whatever substance comprises them, requires another type of substance or God's mind in us. Granted it's easy to confuse the two because we call both 'thought', but they can't be the same thing. God's thoughts produce what we call reality. If we have independent free will, like many idealist's view god to have, then there is a part of us that is not the action of god's thoughts, but actually is the mind substance that does the thinking. If that were the case, then we would also create reality; but we don't do that. When we think, we think, and that is it. It also makes no sense to speak of God communicating with 'us' because that would simply be god talking to himself; actually it would be more like us speaking to the 14,369th cell to the left the edge of my big toe. There is also no way to have separate god substance/mind interact with an action of the original mind, so the whole attempt to put free will in humans doesn't make any sense anyway.
So, there is no way to get libertarian free will out of idealism (in humans) just as we can't find it in materialism. We also cannot derive truly independent creatures out of idealism, creatures that god would talk to in a way that he was not simply talking to himself. The only way to derive an independent creature is to posit a second substance.