That is one strange apparatus. The series pass is a six way Darlington, if that's the right thing to call it.
The final 4 stages draw current progressively from 4 unregulated rails of increasing voltage steps.
At low output voltages, Q1/Q2 draw current from the rail filtered by C1.
With increasing output voltage, a point will be reached where the C1 rail does not have enough voltage so Q2 takes over, drawing current from the C2 rail.
The current from Q2 passes through the B-E junctions of Q1/Q2 to get to the output.
And so on as the output voltage is increased.