Regulated power supply (darlington power) for LM317 10A 1.2..37V

Hello
whether the diode d22-20-04 in this power supply must be

It does not have to, but it is indicated - and not necessarily such but generally silicon rectifier for a minimum current of 20A and a voltage of 300V and above. It is a protection of the power supply electronics against reverse connection of the receiver being the source (e.g. a battery).
See author's post # 45 for first paragraph layout.