You seem to think the term "free will " refers to some other concept. What do you think free will is?
The defying of physical determinism. That is, when presented with an option, there is no way to predict what the individual will choose (given the choice is free and the user wills something). If there's a way to predict, the choice was never free to begin with and thus is not free will.
What's being talked about here is psychological will, which is indeed deterministic.