when opening version 2020 and older versions on my mac. I try to generate speech. the program freezes every time
It may be an issue with the generated voices on macOS. Audition calls upon the voices on your system. If they're not installed it may cause a crash like this.
Open System Preferences > Accesibility > Speech then drop down the System Voice menu, click Customize...
Here you will be able to tick and install voices.