Go to my art packs page.
Click on the “BUY” button of the item that you want. It will take you to a website where you can buy a “digital art brush” named after the art pack you want.
Once you bought and downloaded the product, you should find the password as the 8-digit-long file name of both the ZIP file itself as well as the two files inside the ZIP file. It should look something like “ABCD1234.filename”. Remember that file name (without the “.zip” or “.png” etc. - so just the “ABCD1234” part). If you want to be extra sure that you have the right key, you can also just copy the file name.
Once you have the key, return to the art packs page and click on the “DOWNLOAD” button of the art pack you just bought.
Enter the 8-digit password key you got and voilà! You got yourself an art pack!