Error Code 00000008:ffffffffffffffff

@TheSaturday6  Just so you know, the Sims Delivery content is always incorporated into a later patch, so you're only missing the items for a short amount of time.  I know that's not a real answer; I'm just saying the problem doesn't always have a practical effect.

For the problem itself, try running Origin and Sims 4 as an admin: right-click on each shortcut and select "Run as administrator."  I take it when you did "the rename thing," that means you renamed the Sims 4 folder in Documents\Electronic Arts, but if you haven't, please do so now.

If running Origin and Sims 4 as an admin doesn't help, I'm curious whether you'd see any difference in a new admin Windows account.  Since Sims Delivery content is initially downloaded into the user folder in Documents, you might have a permissions issue with that folder, and a new admin account means a new Documents directory.  I'm not suggesting you abandon your current user account, only that this is a useful test.

Hi! Thank you for your help! I ran as an administrator and it did not help. I don't know how to make a new admin Windows account and Google makes it look difficult. Do you know how to fix the permissions issue on this account? This is the only account on this computer. Could it be a Windows Security problem?

@TheSaturday6  I don't know whether this is a permissions issue for this particular Windows account or not.  The point of creating a new admin account is to test that theory: if the new account can download the SDX content, then the current account is the issue.  But if the download fails in the new account, we need to look elsewhere.

Creating a new account is not difficult at all and should only take a couple minutes at most:

https://support.microsoft.com/en-us/windows/create-a-local-user-or-administrator-account-in-windows-20de74e0-ac7f-3502-a866-32915af2a34d

However, if you'd prefer to try something else first, you can use the "takeown" command on the Documents directory to reset its permissions.

• Restart your computer, and don't open any applications
• Hit Windows key-X and choose either "PowerShell (Administrator)" or "Windows Terminal (Administrator)," whichever option is offered
• In the window, write this command:  takeown /F "[full file path]" /r  with the quotes.  In this case, you'd write "C:\Users\[your username]\Documents" except with your actual username inserted.
• Double-check the command (take note of the three spaces in the command line), and when you're satisfied, hit Enter
• Restart your computer before testing

But if this doesn't work, it's still worth testing a new admin account.

I tried a new admin account and the error still happened.Thanks for your help!

I realized my last message might have sounded sarcastic. I just didn't want to not say thanks so I added it to the end, but I had the tab open and just reread it and it sounded rude to me. Sorry if you read it and thought that too!

@TheSaturday6  I didn't think you were being rude or sarcastic, but then I tend to give people the benefit of the doubt if their previous posts have been pleasant, as is the case here.

You said you disabled your security, but did you also check your Controlled Folder Access settings?  If not, please disable that too, at least long enough to test.

https://crinrict.com/blog/2019/03/windows-10-defender-controlled-folder-access.html

I'd also like to know what security software you're using.  A few other people have reported the same issue, and I'm curious if there's something in common among you.

Oh good! I am using ESET and I am on Windows 11. I looked around in the settings on Windows Defender and did not see the Controlled Folder Access because it just has options for ESET.  

@TheSaturday6  That's not unusual: Windows Defender usually disables itself when it detects a third-party antivirus, since having two security programs running side by side can do more harm than good.  (That doesn't always happen, hence the need to check.)  I haven't heard from anyone else who uses ESET, but then not everyone has listed their antivirus yet.

The only other suggestion I have at the moment is to try using your phone as a mobile hotspot.  (Make sure it's using data, not your home wifi.)  The point is to try a different network just in case there's something about your current network that's not getting along with the SDX downloads.  That would be odd considering that Origin connects without issues, but it's easy enough to try.  If you happen to have a desktop without built-in wifi, I don't think it's worth buying a separate wifi card; this is more of a long shot.