Fix loud and distorted audio

I'm afraid that since you have no original undistorted reference, there's absolutely no way you can 'fix' badly distorted audio. And that goes for all software, not just Audition. And that is a lot of distortion you are looking at - even if you run Effects>Diagnosis>DeClipper on it, it's not going to make a lot of difference, as this can only deal effectively with single overshoots, not massive blocks of them. We've tried running badly distorted audio though the on-line Speech Enhancer, and it still runs into the same problem - and in most cases succeeds in making it even worse. I'm afraid you are stuck with it.