According to Molinism, what is the meaning of a counterfactual of freedom?

If I understand correctly, Molinists consider it important that counterfactuals of freedom ("If person P experienced circumstances C, she would perform action A") are meaningful. In fact, if I understand correctly, the crux of Molinism is the doctrine that the truth or falsity of a counterfactual of freedom is logically prior to Creation. But I'm struggling to understand what a counterfactual of freedom even *means* from a Molinist perspective. It seems clear that the circumstances C do not *logically entail* the action A; we can coherently imagine P experiencing circumstances C but nevertheless refraining from A. But if I understand correctly, Molinists endorse a libertarian notion of free will, in the sense that the circumstances C do not *cause* the action A, either. So in what sense is A the unique action that P "would" perform, were she to experience circumstances C?