Yeah, it needs DirectX 9.0c, the June 2010 version. It's totally fine to use DirectX 9, so no worries, haha.
I don't know why I've been using Classic all this time, to be honest. It's really buggy, and it has some serious memory leak problems. It's like using an old laptop that's running Windows 2000 - its last update was 10+ years ago, and most modern software break or just downright don't work - but man, it just keeps on chugging along. XD
C2 does have some quirky bugs, but I think it's much more reliable than CC. Make anything larger than a jam game with the latter, and you'll find yourself closing and reopening it every 15 minutes. As for C3, I don't think I can ever afford that SAS model they're using. Sad for me. ):
Thanks! DirectX 9.0c is totally safe, so you should try the game out! :D