High Sierra introduces new security features that block legacy kernel extensions (kexts). You must prepare the OS to accept the old Avid drivers.
The standard Apple Installer will read the Pro Tools installation script, detect High Sierra, and throw an error stating that the software is incompatible. We use Pacifist to extract the software manually. Mount the Pro Tools 10.3.10 .dmg file. Open and click Open Package . install pro tools 103 10 on high sierra