I am afraid this particular unit is not for you. Over here we run our appliances with 230V whereas you guys have 110V and you cannot change the input voltage on the unit.
But you could get a 110V version from OSA directly.
Generally this unit would probably be better suited for the Raspi 3B+ and down as you could run them on one channel only and use the 2nd channel for a second Raspi or an DAC with an isolator board (one channel would run the Raspi and the other the Isolator board and the DAC).
However the unit should run a 4B as well if you run the in parallel mode. I cannot confirm this as I do not have a 4B but I am pretty sure this will work. In doubt check with OSA via E-Mail.
I do not have wiring diagram or instructions but setting it up is fairly straight forward: If you look at my picture you see the small block with 3 screws on the right. This is were the mains get connected.
On the left hand side ist a block with 4 screws. This is the 2 channel 5V output.
To run the unit in parallel mode you would just connect the positiv to the positiv side of channel one and your negativ to the negativ side of channel two.
For a 3B+ etc. you would just use the negativ side of the same channel.
Hope this helps…