You would connect the Pool Pilot to the same relay that controls the filter pump. Whenever it gets energized, the Pool Pilot would come on also.
From there, you set the Purifier Output % to maintain the chlorine level you desire.
Test your chlorine, set the % to 50% (as a starting point). Let it run a few days and retest your chlorine level. Readjust the % higher or lower, depending on your test result. Let it run a few days again and retest and readjust as needed.
Once you're maintaining the your chlorine level, the automatic temperature compensation should help mainitain your chlorine levels for water temperature changes. That is, as it gets warmer, the % setting will increase automatically, and as it gets colder, the % setting will decrease automatically.
The only times that you may need more chlorine is for inclimate weather or pool parties....or shocking the pool.
You can use the BOOST button to do this, or you can add chlorine (bleach, tabs, or cal hypo).