I had alot of issues with the coding. You have to install both the zip file, and the additional libraries.
Make sure to update the amount of LEDs per strand in the IDE brlefore upload. Mine has 103 LED's and not 24
The direction of data flow should be the same, unlike the picture reference.
I had to use the 5mm slim LED's as the 10 mm did not fit properly.
Make sure your feather board is the unassembled one as the one with pins pre-installed causes issues.
I had to correct the terminal position on my battery, it was opposite of the pictures.
Other then that, it was a fun build!