For whatever reason, sometimes, a browser addon or extension might be available to download from the Google Chrome Store or Firefox Add-ons page and magically disappear. Usually, it's because somebody is messing with someone else's money and becomes a bully.
Here are some of my favorite “sideloaded extensions” for my chromium based browser:
You'll have to enable developer mode in your browser extensions options page (usually a toggle option in bottom left corner) and when you download the addons, just create a folder on your desktop, extract and in the browser click the Load unpacked button.