Pro Tools 12.8.3 for Mac is a legacy version of Avid's industry-standard digital audio workstation (DAW), originally released on , to provide official support for macOS High Sierra (10.13.2) and the iMac Pro. To download this specific version, you should use official Avid channels:
You would need Pro Tools 2019.6 or newer. Pro Tools 12.8 3 Mac Download