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.
Thanks for the efforts with the script Louis.
I found some things that needed tweaking but I ended up writing my own from scratch for fun (as I wanted to make it more flexible for people with different settings or who want to change things).
I also made a simple download script since this only adds assets to an account (if anyone wants it - feel free to go to my GitHub to grab it).