The paper models a 40 t lander. That's roughly Blue Moon. The sum of all Chinese probes landed on the moon is far less than that, and I wouldn't be surprised if the sum of all Soviet Luna landers was also less than that.
As noted, the paper is referring to a 40 t lander with a single 67 kN thrust engine.
As some other data points, the Apollo landers were 16t (later ones a bit more for an extended mission). The ascent module had a dry mass of 2445 kg and had an additional 2376 kg of propellant (5t).
The lander's descent propulsion system was capable of 10,500 lbf (47 kN) that could be throttled between 10% - 60% and 100%. (1,050 lbf (4.7 kN) and 6,825 lbf (30.36 kN))
The ascent propulsion system was 3,500 lbf (16 kN).
