In case you tried to download mac OS Big Sur today and got the message: "Installation Failed: An error occurred while installing the selected updates", you are not alone. It turns out nearly everyone who has tried to download the new mac OS has gotten the same message and has been unable to download it. Apparently Apple's servers are down and they're in the process of getting it fixed.
macOS Big Sur is a big deal in that it is the first macOS to leave OS 10. It’s predecessor macOS Catalina, which I’m currently running, is OS 10.15. Big Sur is 11.0. macOS Catalina helped make the transition to 11.0 by dropping 32 bit apps and only running 64 bit apps.
One more detail on macOS Big Sur is that Apple delayed its release by quite a bit. Catalina was released October 7, 2019, Mojave was released September 24, 2018, High Sierra was released September 25, 2017, and Sierra was released September 20, 2016. As you can see, a November 12 release date is significantly delayed from the typical early fall release dates that Apple tries to follow. It seems as though Apple had more bugs to iron out with this new OS and then combined with everyone trying to download it at once, we have the mess that we do now.
Anyways, if anyone is able to get it to download, feel free to comment below. I’ll let you all know what else I find out and when I’m able to finally get it downloaded. The YouTube video I have linked below is what confirmed to me that it wasn’t an issue on my end. You can also check there for more updates in the comments section as well.