I will try to get a refund from my primary school.
According to this video, this 12V strip consume a lots of energy even when idling. I don't like this fact but unfortunately there is not many choices for me when it comes to 12V strip.
The WS2811 is not individually addressable but in a group of 3.
I might have to consider lowering the density of LEDs/m from 60/m to 30/m if I am not feeling comfortable with the amount of current in the circuit.