When purchasing the Cube you need to change "I'd like to donate:" to "Other" and change the amount to $1 and complete checkout per normal.
Be inspired with the Joel Osteen Audio cube: featuring 365 daily Inspirations, 52 sermons and 31 affirmations. Or you can pull out the SD card and put whatever you want on it per the below links:
https://twitter.com/foone/status/1338645260323356672?lang=en - I used this guide as it seemed easier.
The cube is also a high quality Bluetooth speaker and it does sound pretty good.
The only down side is the charger is for US plug and it took about a month to arrive. But as it is a donation and the cube is a free gift so you can probably deduct on tax? Edit: turns out it's not Tax deductible :(
I made up a basic Excel sheet to rename the files with rather crude instructions: https://drive.google.com/file/d/1cSjhTuxigi_6qNZyvEG0pyAx3b_...