HT16K33 with "standard" leds

Hi all

As first 'real' project, I wanted to make a rocket control board; lots of switches and leds all over the place. (see here)
While researching I found that I should go with a HT16K33 from holtek to drive as many lamps as possible.

I have wired it according to the schematic from holtek documentation (here).
I opened the arduino ide and used the adafruit libraries (i didn't find any other) and used the function Drawpixel.

Off course it didn't work.
the whole point is that I don't really understand what I'm doing. I know the ht16k33 board recieves 5V as intended. The circuit from the A0 pin to the C0 pin is a working circuit, but I have absolutely no idea if I use the correct I2C adress, if the commands arrive on the board and if they really are instructions to turn on [0,0].

Can someone give me pointers on how best to troubleshoot this?