downloads crashes my game

Are you downloading through the ingame store ?

If so, close your game and try downloading through the launcher instead.

I bought the download in store, however it's not showing up on my launcher. I've opened the downloads dashboard in game to try downloading but that's when it stops

Try this

1. Close the game and launcher
2. Start Origin
3. Click play to start the launcher again
4. Start a browser of your choice and go here: https://store.thesims3.com/purchaseHistory.html
5. Download from there.
6. Install in the launcher after downloading.