Very helpful. Thank you@Karl-Hungus,
Occasionally this happens to me, too. I either wait to the next day or go to this site:
Download macOS Monterey full installer with one click straight from Apple! Every version of Monterey Beta & Final available all in one place!!mrmacintosh.com
SIP enabled, Nvram has been reset and did not solve the problem as people have suggested here...
HI, I've been trying to download Mac OS update... the servers are definitely full. I tried for 5 days straight till finally last night I was able to download it in full but my iMac 2020 computer won't let me install it. I have plenty of extra disk space but it constantly fails. I have the download and can't even get it to install.