There was a study on 21 macaques that were fed infected muscle meat, infected brain meat, or were injected with the CWD protein. Some of the macaques became infected and were euthanized. On this hand, it is supposedly possible that humans could get CWD, since some of the macaques did.
One the other hand, I believe there is a separate study concluding that some of the macaque’s proteins were the same as cervids, allowing infection, whereas human proteins were too different from cervids to allow infection. This actually holds water as a prion is known in goats and sheep, called Scabies, that have never infected humans. Scabies have also existed for a long, long time. Since Sasquatch is very likely to be incredibly close genetically to humans, it’s plausible that they simply can’t, or very very rarely get CWD.
Regarding how Sasquatch and other animals avoid or deal with prions; prions are slow acting and unpredictable. They can become symptomatic in just a few years, or not at all.
Its plausible that Sasquatch and even other predators would shift their diet to other animals if the disease would become too much of an issue over time, or not selecting parts of the animal that are likely to carry the prion (brain, spinal cavity). In fact, do most predators routinely avoid brains and the like? Much like how many predators avoid some other organs like parts of the digestive tract, perhaps predators avoid brains due to prion diseases? I haven’t been able to find any evidence for or against this.
I will say that prions really aren’t a massive problem for the non-host species. Heck, many animals that are members of the host species may never develop the effects of a prion disease in the first place. I doubt this disease is majorly affecting, or even having any effect at all, on sasquatches.
I will try to find the two studies if I can.