Can't see the picture and the link doesn't work.
Permeate is the good water that has permeated the membrane. Therefore, a permeate pump is used to pump the finished water to storage or to some point where it will come out of a faucet so you can use it.
Without the diagram showing how the system is supposed to work, it is hard to tell you what you need to do. What make and model is the the system? Can you post a link to the manufacturers site where the system diagram is shown?
If your storage tank is a bladder tank, it may be that permeate pump goes from the product outlet of the membrane to the storage tank.
Without any idea of your system, we are all at sea with no compass. If you don't have a diagram and pretty good instructions on how to operate and maintain the system, then you are at sea with little hope of reaching shore.