The horizontal chamber is the ro membrane. It sounds like there is no flow restrictor on the waste tube. The restrictor causes pressure to build up at the membrane forcing some of the water to pass through. The rest is wasted. Without the restrictor, all your input will flow to the waste line.
What ro unit did you buy?
The first thing I would do is block the waste water line and see if water passes into the other chambers and out the blue line. You should be able to block the waste water just with your thumb. If that doesn't produce water in a minute or two, you may have some other blockage.
Try the above and report your findings.