The Principle of Causality, Mathematics and Forecasting

Good day!
The Chazo wrote a reply (it was printed on Taharat and censored) to the question of what is the reason for God, that just as a mathematical formula exists even if there is no material world and will always be true, that is, one that is not subject to the limitations of space-time and therefore not to causality (and as I understand it, he means physical causality and not logical, and from this we arrive at the problem of induction and the question of Leibniz and the ACM), that is, one that has the ideal status of truth, so too is God an eternal being that is not subject to material limitations.
And my question is: Apparently the Chazo'a simply assumes that mathematics has an eternal, essential status that exists even without material reality, and yet he actually assumes, like Plato, that there are ideal concepts (he did speak of essences such as good and evil and all categories of thought, but apparently this is the case. And by the way – what is the status of music, does it have an ideal status or is it just a description translated into sound of the interrelationships of matter?), but if we assume, like Aristotle, that all essences and properties are categories that describe matter and nothing else, then if there is no world, there is also no mathematics and apparently there is also no truth (which, according to him, truth is only a relation of correspondence and nothing else), since there is no such abstract eternal reality, and in any case it does not belong to the Chazo'a's definition?
Another question: According to Plato, there is a 'world of ideas' that is not connected to material existence, and I don't understand: Where is it? In what sense does it exist? Does it exist ontologically?
Thank you very much!