Yes, that's correct. There is no global dipole magnetic field on Mars [1]. However there are weak fields "frozen" into some of the oldest rocks on Mars [2], which indicates that the planet did have a global magnetic field at some point in its early history. Scientists think that the lack of a global magnetic field was part of the reason that Mars lost its atmosphere. [3]
For humans to settle on Mars and stay for any length of time, we will need to find a way to shield ourselves from the ionizing radiation that reaches the surface. [4] On Earth, most of this radiation is either deflected by the global magnetic field, or absorbed by the atmosphere.