facing issues in signing using apple id and appstore not working properly after downloading Version 15.0 (24A335) [Sequoia] system update

+1 I was also having trouble signing into one of my Mac mini's after upgrading to Sequoia.

The fix was to open the App Store and sign in there first.

Check your Firewall settings.

see > Change Firewall settings on Mac - Apple Support

First go to App Store and install load

MacOS Sequoia‼️‼️‼️DO NOT DOWNLOAD YET‼️‼️‼️next go to settings, click on your name above, Scroll down and sign out. Log back into your Apple computer account and go and download the new macOS version and Bam. You should be up and running. Sometimes you have to sign in and sign back out. You gotta look at it just like if you had to turn off and turn your phone on to get things to work properly

I'm one of the unfortunate ones that has a separate Apple ID for Media and Purchases than iCloud. So logging into my Media ID doesn't help. When I go to system settings and click on my apple account (where my pic is) the page won't load. It stays on whichever window I was on before hand. Oddly, I went into network settings and disabled ethernet and wifi and it let me go to the Apple ID screen. As soon as either form of network is restored no joy. Even more interesting. I read that turning off "Limit IP Address Tracking" off helped. AND IT DID! and then it didn't again. Also turned off firewall. No joy. During the brief time I was able to access my Apple account page I noted that iCloud Drive was off for syncing. I tried to turn it on as none of my documents have sync'd with my Mac mini since restoring from my Time Machine Doc. No joy. Then I was hosed for getting back into iCloud settings. I stumped the senior apple advisor as well. TIA for help! Running Sequoia 15.0.1 on my 2018 Mac mini. Hardware was checked and was ok.