@brookemorgan20Of course not - it should be in your game library.
Your expansion pack you will find when in Library right-click on the cover of TS4 - option "show game data"
It will on the at the bottom of the page
What kind of info you have when you are looking for an option to download your game expansion from Origin library? Are there no option "download" on the cover of the expansion pack? Maybe there are no expansion packs?
If you don't have the option "download" or there are no expansion packs - uninstall Origin using the Revo - free version
https://www.revouninstaller.com/revo-uninstaller-free-download/and download Origin once more from here
http://origin.com/downloadIf you have this option but the computer stops this installation, check if your antivirus/firewall/Windows Defender isn't blocking it.
I don't work for EA