Go to the Effects menu, select Time and Pitch , and then click Automatic Pitch Correction .
I notice you're asking for an "Autotune VST" for — that's a very old version (released around 2004). Autotune Vst For Adobe Audition 1.5
Place the AutoTune.dll (32-bit only) into C:\Program Files\Adobe\Audition 1.5\Plug-Ins\VST . Then go to Options > Device Order > VST Effects and click “Refresh List.” Go to the Effects menu, select Time and