Normally, the configuration of the booster pump with your R.O. system should be as follows:
Pre-filters ------> Booster Pump ------> Shutoff switch ------> membrane, etc.
The pre-filtering will minimize the sediment which can enter the pump (and possibly damage it).
If you have a pre-existing automatic shutoff valve on your system, you may remove it and reconnect the necessary tubing.
The pump has a wire coming out of it -- connect this to the transformer.
Connect the wire from the transformer to the tank shutoff wire.
Connect the tank shutoff to the electronic shutoff switch.
Connect the electronic shutoff switch to the motor.