Go to https://www.mixamo.com/store/#/search?page=1, make sure you're logged in.
open up chrome console by pressing F12 on your keyboard on the Mixamo webpage. Click on the "Console" tab in the new window (developer console).
Paste in "DownloadMixamoByLouisHong.js" into the console input and return. It'll starting downloading from that page and until the last page.
Wrote a new script to download all mixamo animations for a single character
https://www.youtube.com/watch?v=EuAjnKAehGI&t=5s