[CURRENT ISSUE] Sims 4 already running

@ajptwo  Your computer should be able to run all current Sims 4 content; its hardware isn't the issue.  And this error isn't due to hardware anyway, nor is it related to the download issues that can happen when the CAS Demo is installed.  (That's completely separate.)  Instead, it typically happens when Sims 4 can't access or write to the user folder, as in, the Sims 4 folder in Documents > Electronic Arts.

I see a OneDrive sync error in your dxdiag, so that's the place to start.  First, find the Sims 4 folder in Documents > Electronic Arts and make sure it's the one with your saves inside, that is, if you have any saves.  Right-click the folder and select Copy, then paste it on your D drive: open File Explorer, click This PC, then double-click D, and right-click in the empty space and select Paste.  This will be your backup copy of your saves and other user files in case you need it later.

Now please pause OneDrive syncing and cancel the current sync:

https://support.microsoft.com/en-us/office/how-to-cancel-or-stop-sync-in-onedrive-4885c27e-3d89-4d69-be75-2646c71367d3

Next, tell OneDrive not to automatically sync the contents of Documents.  You'll stlll be able to manually upload files, but it won't keep interfering with Sims 4.

https://support.microsoft.com/en-us/office/choose-which-onedrive-folders-to-sync-to-your-computer-98b8b011-8b94-419b-aa95-a14ff2415e85

Restart your computer and try again to play.  If you get the same error, please let me know the full file path to the Documents directory: open a File Explorer window, right-click Documents in the left panel (the one with the special icon), select Properties > General, and list the Location.