You can play online with your friends through cncnet.
Download and install the CnCNet client from their official website.
Launch the CnCNet client and create an account.
Once you’ve created an account, click on “Red Alert 2” in the list of games.
Click on “Download & Play” to download and install Red Alert 2.
Once the game is installed, click on “Play Online” to start playing Red Alert 2 online.