The OS X system should be able to run the game. The graphics adapter meets the minimum requirements, but a recent driver version should be installed. As @Geneo stated, it's far from perfect. But when reducing the graphics settings (especially disable SSAO and Lightscattering, both are performance killers) and reducing the view distance it should be fine.
The Ubuntu system most certainly does not work, the CPU isn't the problem I guess, it's more likely the graphics adapter which is insufficient ![]()