The study shows our primitive mind makes a lot of decisions for us. But nothing about free will.
Exactly. In fact, better studies have even shown that some pre-processing of visual information occurs before the signal even reaches the brain. This reinforces the conclusion that much of our cognition is essentially prior to the activity of consciousness, even though consciousness would be a presupposition of free-will. (For example, my mind determines that a glyph on a screen is the letter L and then sends my consciousness not the raw pixel data, as it were, but rather the glyph pre-interpreted as an L; once within consciousness, I may or make not make a decision in regard to this glyph.) Thus the only relevant statement that the present study can make with regard to free-will is that fast-paced declarations about the imminent future may be at least partially determined in advance by preprocessing that occurs prior to the full experience of consciousness.
Note that I say "declarations about the imminent future" and not "choices" or "decisions." This study does not really deal with free-will directly because the participants are not necessarily even intending to make real decisions but only to pronounce upon the future. (Some may even interpret this as a kind of "psychic" prediction.) Hence their conscious minds are essentially tasked with acting like random number generators. But it is no surprise if we are bad at being random, just as computers are not fully random. If you ask me to come up with a random number, I will almost certainly pick a number that I am already predisposed toward picking because of the situation around me, or because it is one of my favorites, or because I am trying to be crafty, or because it happens to currently on my mind, etc. I can never be certain that any random number that I generate is truly random.
But free-will is not reducible to randomness, and therefore a lack of genuine randomness is not tantamount to a lack of free-will. Free-will is not the ability to do something random, nor the ability to be absolutely undetermined by outside influences. (Ironically, this study, implies that free-will in this case would be the ability to be wrong about predicting colors.) Ultimately free-will is the ability to decide about oneself to take up the mass of conscious data and concrete, pre-determined factors and to weave them into a connected narrative of selfhood. Thus free-will is not incompatible with any kind of predetermination whatsoever. Quite the opposite, when we experience ourselves as having made a free decision, we can also look back at that decision and see that it "makes sense." Hence I experience myself as freely deciding to eat lunch; but this makes perfect sense because I am hungry, I have a lunch on hand, I am used to eating lunch at this time, etc. We are too used to looking for ridiculous exceptions in order to try to prove free-will, like I need to make a decision that makes absolutely no sense at all. However, free-will is something that--at least according to our own conscious experience--occurs not simply in such extreme and exceptional cases, but even in the most mundane and predictable parts of conscious life.