femtonyl You shouldn't need to login in order to install Store content. The fact that you're asked at all is the issue here.
Please try installing Dragon Valley in a new admin Windows account. Make it local, as in, don't link it with your Microsoft account or any email address. You'll be able to play and use the launcher without reinstalling anything, but your saves and other user data won't be available. That's fine for now and can be addressed later if necessary. For now, just see whether DV installs in the new account.
If it works, that means the problem is limited to your main Windows account, which is great. If it doesn't work, please let me know whether you've ever had two EA accounts merged, had an EA Play subscription, or asked for a refund for any Sims 3 content.
