Running Windows 10.
No point in beating a dead horse or bashing staff. The game is entirely free to play, and for that, I am eternally grateful. For those complaining, realize that Mac users went without the game for about a month or so, and didn't act nearly as childish as a handful of people I'm seeing. It hasn't even been a full day. Give it time, and I'm sure it'll be fixed. Things happen, code breaks somewhere, it's technology- it's not perfect.
It is worth noting, if you use Avast or any anti-virus that picks up on the 1.30 launcher as a virus, temporarily turn it off to download the game. Many anti viruses detect the launcher as potential malware because it lacks a reputation base.
A solution I found is to simply redownload until it works. This isn't ideal, but I did a clean uninstall of the game (using the native uninstall tool) and reinstalled using the 1.21 launcher. Previously, it would inform me I had an update available and shut down, and open a webpage to the game launcher download.
However, as of 23:04 CST, I was able to update the game successfully and launch.
Hope y'all's problems find solutions. Patience is key here.