Reading and interpreting output sensitivity of a load cell from data sheet
I think that what they mean by "Output Sensitivity" is what is also sometimes referred to as the "Full-Scale Deflection", and the reason that they are not giving it a unit is because it is relative to the supply voltage, or here "Excitation Voltage", which they require to be between 3V and 10V.

So in other words, this is how I would calculate the parameters I need to use this sensor;

First we choose a supply voltage between 3V and 10V, lets use 3V for this example.

Vcc = 3v

Now we calculate the Full-Scale Deflection voltage, ie. the voltage out of the sensor when the sensor is under full load.

Vfsd = Vcc * 0.7 = 2.1V

Now we look at the range of the sensor which is 0-200kg, from this I would assume that Vfsd corrosponds to 200kg of load on the sensor, so to calculate the output voltage (Vo) pr. kg of load on the sensor we simply divide;

Vo = Vfsd / 200kg = 2.1V / 200kg = 10.5 mV/kg

To this we have to add an error of +- 0.15 mV/V, so at the full scale deflection the error will be;

Vfsd * 0.15mV/V = 2.1V * 0.15mV/V = 0.315mV