You can still be a determinist. The "probabilities" that quantum mechanics calculates are purely epistemic. The reality behind them is still up for grabs.

If you are wedded to the notion of single histories, then you could be, along with Gerard 't Hooft, a superdeterminist. This is the sort of determinism that takes account of quantum entanglement effects. There is no free will in this picture, as far as I can tell, but Prof. 't Hooft claims that is irrelevant to what humans actually do. I'm not so sure.

If you accept the reality of alternative histories, then you can still be a determinist if you stick to unitary time evolution of the wavefunction, i.e. you abandon the notion of wavefunction collapse. The implications for free will in this picture are not fully worked out. There are some big names who think that Many Worlds guarantees free will, while others are sceptical. So, if you are an Everettian of some sort, you are certainly a determinist, but you might also have free will. There is an ongoing research project called "Constructor Theory" that seems to have a theory of free will as one of its (distant) goals.

This is quite entertaining:

You can still be a determinist. — Inis

That, I think, is correct. "Probability" doesn't mean "Free will". I don't even understand the non-deterministic nature of the quantum. Is it a fundamental property of matter/energy or is it just a hole in our knowledge? Heisenberg, if I'm right, claimed it's the former and that nothing can change this "strange" nature of the quantum. Are there others who think differently?

Another thing is that consciousness seems to require complexity rather than simplicity. In short we need a brain with a 100 billion neurons and supporting structure. If that is true then consciousness is a property of a higher level of matter-energy organization. A bacteria is too simple to have consciousness to say nothing of an atom or electron. Higher levels of matter-energy organization work on deterministic principles don't they? Isn't that why we have the issue in the first place?

We see all matter-energy that we can actually perceive of following strict laws of nature. Therefore, the determinists say, determinism is true.

I think the first thing to understand would be consciousness itself and, specifically, at what level of matter-energy organization it exists. If consciousness is a quantum phenomenon, which I think is unlikely, then there's room for free will. On the other hand, if that's not the case then free will may not exist.

Very good answer Inis