It does not say anything about Proxima b having a magnetic field, but I found this paper where a magnetic field for the planet is predicted:
In our simulations, most Proxima b analogues develop intrinsic dynamos that last for 4 Gyr (the estimated age of the host star). If alive, the dynamo of Proxima b have a dipole moment . These results are not restricted to Proxima b but they also apply to earth-like planets having similar observed properties.
My question is if an Earth-like magnetic field, if Proxima b has one, could protect life as it does on Earth, or, conversely, habitability could not be possible due to stellar wind.