Don't worry about the word. It's some kind of a metaphor. In other words, Einstein believed that we have no free well and the universe is deterministic. Quantum Mechanics challenged that belief.
Einstein thought the universe is deterministic, but I do not recall him claiming free will does not exist.
In fact, I am not even sure free will versus determinism is even the right question.
We view free will through the prism of cause and effect, through our conscious perception of the arrow of time. Our phenomenological experience of time is that the present is reality, the past is memory, the future is undetermined.
The universe does not care about our limited phenomenological conscious experience of time. Reality for the universe exists simultaneously in the past, present, and future.
Even if the laws of physics imply all future and all past events are known, and reality is comprised of past, future, and present simultaneously, it does not even necessarily mean free will and determinism are at odds.
That is to say, even if the Universe, if God, if Brahma, if the Dao know what is going to happen, it does not mean we did not freely make those choices ourselves.