This estimates your score from the number of questions you get right. It is a simple linear model, not the real curve.
Estimate only. The real digital SAT is adaptive and scored by the College Board.
It gives a rough linear estimate. The real digital SAT is adaptive, so your second module's difficulty depends on your first module's performance. College Board's actual scoring curve is not public.
Reading and Writing has 54 questions across two 32-minute modules. Math has 44 questions across two 35-minute modules.
Each section ranges from 200 to 800, so the total ranges from 400 to 1600.