Sims 3 Store Content Won't Download

@transonlyocean  I think it's very likely that Midnight Hollow isn't installing because you moved the Sims3Pack from your old computer.  Store content, unlike custom content, is encrypted and doesn't always transfer from one system to another, although it should in theory.  So you'll have to download a fresh copy.

On that note, please try using Firefox if you're not already: it works better with the store than other browsers.  If you've already tried Firefox, clear its cache or use a private browser window.  For the welcome screen, set Edge to open sites in IE mode.  If you have already, try clearing Edge's IE data (end of the article):

https://support.microsoft.com/en-us/microsoft-edge/view-and-delete-browser-history-in-microsoft-edge-00cf7943-a9e1-975a-a33d-ac10ce454ca4

Neither idea worked ☹️. Any other suggestions? It just keeps asking me to log in and the welcome screen still looks like that.

@transonlyocean  As a test, please create a new admin Windows account and see whether you can login and download store content in that account.  Make it a local account, as in, don't sign into Microsoft, and don't sync with any other services you normally use.  You'll be able to sign into Origin and won't need to redownload Sims 3, although your saves and other user content won't be available.

If this works, the issue is some setting or temp file on your main user account.  We can troubleshoot that further, but if you'd prefer, you can instead just use the new account.

If you can't sign into the store site in the new Windows account, please contact EA customer support to make sure there's nothing wrong with your account.

https://help.ea.com/en/contact-us/