Connect your lights to the Sparkle Motion Mini board as shown:

• DI to GPIO 32: Remember this number for the Config step
• +5v to 5v
• G to G

I also added a control switch to my skirt. This switch can be set up to change modes or colors, or turn all the lights on or off at the opportune moment without having to fiddle with your phone. It's not needed for the project to work, but can add a lot of magic to your cosplay.

Connect the two legs of the switch to the white & black wires of the smaller Stemma port. Either leg can connect to either wire.

I made my project a little more complicated by adding a 3-pin JST connector between the board and the lights. This makes it easy to pull the board out of the project so I can wash the skirt without worrying about damaging it. 

We can power the project through the USB port on the Sparkle Motion Mini. It will support up to a 4A draw, which is different from a lot of microcontrollers: if you did this with the QT Py Pico it could fry your board. The Sparkle Motion Mini is designed for this kind of project, so can power a lot of LEDs.