You will need an auto top off unit...mine has 2 sensors, one for the fish tank and another for the tub holding RO water, if it goes empty the sensor will not switch on the pump so it won't burn out.
Next you need a pump and a piece of hose to run from the holding tub to the tank.
The holding tank or tub can be placed anywhere...the basement, under the DT or at the side of the stand. As long as the pump can pump the water to the tank.
I would not attach the RO water directly to the auto top off..using a holding tub protects you from having a flood if the sensor in the tank gets shifted or goes bad and won't shut off. A flood from a holding tank is allot easier to deal with than an open pipe from your main water supply.