Unfortunately, Firefox has an insufficient buffer to decrypt data in the browser, please install the MEGA desktop app to download large files (or use Chrome)". So I tried Chrome and it worked,
Does Jdownloader now even allow solving CAPTCHAs manually? This page is opened which suggests installing their own extension, not hosted on addons. mozilla.org : r/firefox
JDownloader 0.5.859 - New Interface, Firefox Addon and Many other Changes ~ Web Upd8: Ubuntu / Linux blog
Solved] Where to download Firefox Browser Solver old .xpi AddOn and new *.xpi extension? - JDownloader Community - Appwork GmbH
Download With an External Download Manager - add0n.com
JDownloader.org - Official Homepage
JDownloader Alternatives: Top 10 Similar Download Managers and Video Downloaders for Firefox | AlternativeTo
JDownloader for Ubuntu/Linux Mint/other Ubuntu derivatives - NoobsLab | Eye on Digital World
My JDownloader Chrome Extension, Plugin, Addon Download for Google Chrome Browser
How To Automatically Extract Or Join Files In JDownloader - I Have A PC | I Have A PC
Download with Free Download Manager (FDM) – Get this Extension for 🦊 Firefox (en-US)
How To Schedule Rapidshare File Downloads With JDownloader
Download with JDownloader – Get this Extension for 🦊 Firefox (en-US)
How to master the art of downloading with Jdownloader | Digit