503 error even using different machines

[photoemulator]

• I'm reporting a broken site support
• I've verified that I'm running youtube-dl version 2020.09.06
• I've checked that all provided URLs are alive and playable in a browser
• I've checked that all URLs and arguments with special characters are properly quoted or escaped
• I've searched the bugtracker for similar issues including closed ones

➜ ~ youtube-dl https://stackskills.com/courses/enrolled/76596 --verbose
[debug] System config: []
[debug] User config: []
[debug] Custom config: []
[debug] Command-line args: [u'https://stackskills.com/courses/enrolled/76596', u'--verbose']
[debug] Encodings: locale UTF-8, fs utf-8, out UTF-8, pref UTF-8
[debug] youtube-dl version 2020.09.06
[debug] Python version 2.7.17 (CPython) - Darwin-18.7.0-x86_64-i386-64bit
[debug] exe versions: none
[debug] Proxy map: {}
[TeachableCourse] 76596: Downloading webpage
WARNING: unable to extract course title; please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; type youtube-dl -U to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.
[download] Downloading playlist: 76596
[TeachableCourse] playlist 76596: Collected 0 video ids (downloading 0 of them)
[download] Finished downloading playlist: 76596

I get a 503 error when I include my username and password on the command line. I've tried this on Windows 10, Kali 2020.2 & MacBook (OS 10.14.6). Every one of them gives me the same error and I can't find any info as to why I get a 503. I've tried a single URL, a text file with multiple URL's, flagging it so that I don't have to worry about certificates... It's just not working.