I don't think they're keeping that up to date anymore, just use this: https://gbatemp.net/threads/release-anemone3ds-a-complete-theme-and-splash-manager-for-your-3ds.482804/
All you have to do is get the new boot.firm file. Which is in the zip file of any luma version you are on.So go here: https://github.com/AuroraWright/Luma3DS/releases and download it
So I just updated to the new boot9strap version (1.2) and after following the instructions on 3ds.guide whenever i try to turn on my 3ds, even holding start or select, it just says unsuported launcher. What do I do?