Antares is the company who sells the world-famous Auto-Tune vocal processor. Their products are fine, but their website is awful for numerous numerous reasons, and there's a lot of out-dated and misleading information about their products' compatibility with Ableton Live . I own Live 8 and Live 9, and I've personally stopped bothering with anything Antares makes. Here's why:
Auto-Tune Live, and versions of Auto-Tune EFX 2.1.1 or greater are not supported on Live due to Live's lack of support for the VST3 plugin format. They actually do mention this on their site. But you'll have trouble finding out this other detail: Ableton Live 8 and 9 both have 64-bit versions, but from my own experience with recent Antares products, the 64-bit versions are all VST3, which means you cannot use them in 64-bit Ableton Live.
So, as of this writing, if you're running 64-bit Live, you won't be able to use a 64-bit version of any current Antares product, although you can probably use some 32-bit Antares plugins with some kind of 3rd-party plugin bridging solution, like jbridge. Also, not even 32-bit versions of Auto-Tune Live and current versions of Auto-Tune EFX will run on any version of Ableton Live.
The pitch correction options are kind of limited on Live. Waves Tune is not compatible with Live at this time, which basically leaves Celemony Melodyne.
When doing pitch and harmony correction on Live projects, I sometimes export the vocals to Steinberg Cubase, which has built-in Pitch Correct and VariAudio features, and then re-import the audio back into Live.