As we said before the game is available for free on Origin. The problem is that EVERYONE knew about it and stormed it. Was difficult to get a download going. 
Due to this they had to take it down. They said it’ll be back soon but they realize that the demand for that game is much higher than they thought.
Quote from the site:
Looking for Command & Conquer Red Alert™ 2 and Yuri’s Revenge™?
- Wow, you guys are loving Command & Conquer Red Alert™ 2 and Yuri’s Revenge™ On the House! The demand is so high that we need some time to cool down our servers. Command & Conquer Red Alert™ 2 and Yuri’s Revenge™ will return to on the house very shortly. Thanks for being patient!