I'm an enthusiast (at age 55 more wish I had been than wanabee!) not a pilot and perhaps should ask this question in Spotters but as it's relevant to this incident it makes sense here.
The report refers to an Angle of Attack sensing system which, together with pilot's use of a particular autopilot mode, was key to what went wrong. I'm struggling slightly with what such an instrument is showing and the 'units' in which it measures.
As I understand it angle of attack is determined by (a) wing incidence and (b) pitch. That doesn't need an instrument so presumably the gauge is showing something more complex computed from pitch but also other parameters including airspeed, air density/altitude, flap position etc. Is that right? If so what is the 'unit' being measured?
In practical terms is the key keeping it in 'green zone' by control of the parameters mentioned above?