@3MummaBee  Sign into Origin or the EA App with the same email address and password you used on the old Sims 3 site (the community site you referenced), and Sims 3 should already be present in your game library.  Origin is probably the better bet than the EA App, at least for now.  You can download it from here:

https://answers.ea.com/t5/Origin-Client-Web-Technical/Downloading-and-installing-Origin-Windows-and-...