this looks different from yours.
but substitute the di for post carbon and put the pump between the filters and the RO membrane and it would be the same. i would look at what the barrel floats are doing. are they upside down? has this worked in the past ,just not now or has it never worked? good luck
Got it figured out. Thank you all! I added a second membrane and it did not have a check valve. I also moved the booster between the carbon block and first membrane.