Before you go charging full speed ahead, you need to look up what the logic voltage on the blackpill is. I’ve never used one, so you’ll have to check that for yourself.

If the blackpill’s high voltage is 3.3v, then an RGB running at 5v will likely not recognize 3.3v as high (or as a binary 1 if that’s easier to think about).

There are two ways to get around this, either power the RGBs from 3v which is out of spec but will work (they will be dimmer though, and again this is out of spec), or shift the blackpill’s logic level to a higher voltage. You can use a diode to accomplish this, with this fiendishly clever hack.

If you need to use either of the above approaches, probably a good idea to breadboard it first before shelling out for the PCBs