Give these a try:
The game is grayed out in Origin
First you need to check if your payment has gone through. Unless your order says fulfilled, you won't be able to download. If you have issues with your payment, you'll need to contact a game advisor.
- Log out and back in
- If you are on a mac, make sure you download Origin for Mac.
- Check on the Status of your order to see if it has processed. If it still saysprocessing, make sure your credit card info is up-to-date
- Restart Origin
- Reinstall Origin
- Start Origin as administrator
- Make sure Origin is online (click on the spoiler below to view an exemplary screenshot)