Quinn's Aquarium – Rank Still at 0

Hi.  Today is my first day on Pogo.

On Quinn's Aquarium, my Rank never goes up.  Which of these is the problem (or is it something else)?

1. I will have to find all 6 Shell Sets in a puzzle to be awarded a boost in my Rank at the end of the game.

2. I will only receive Rank when I complete the cleanup and repair, etc., of the individual aquariums, so I will have to complete a whole "level" before I see my Rank move up.

3. Rank will only accumulate if I am a paid member.

As you can probably tell, I am not a paying member (I forget what it's called – a Pogo Payer, let's say), I have not yet completed my first aquarium setup (though I've played several puzzles progressing toward fixing up the first one), and I've not yet successfully collected all 6 Shell Sets in any puzzle I've played.  So, I imagine one of these three things is the problem.  If not, my only other guess would be a bug.

OK, I look forward to your answers!  Thanks in advance!