Biasing circuit - Voltage follower circuit
Although your assumptions were wrong and the spec is correct, I found it hard at first to understand because of lack of details.
A full schematic, layout, and bill of materials are available upon request.
Also, ask for details on an external layout for testing.

Pin 1 &amp; 3 are connected to DUT input as the voltage follower (internal Op Amp)
Pin 4 is the non-inverting input. from VR1 from -8 Vdc .
Pin 6 is TTL input pulses to drive Q1 Pch to pull up the DUT
DUT is the QPA1022 4W 8.5 –11 GHz GaN Power Amplifier shown in Fig 1 for North Side bias.  


Pin 8 = Vds= 50V  , Pin 7 = Gnd

Pin 5 = -8V, Pin 7 = Gnd




I see no evidence of pin 2 = NC connected to anything. (external only) Most likely a Test Pin. Perhaps why they said do not ground.
Pin 6 is also NC but connected to pin 12, so I suppose those are interchangeable interconnects.