See the Pro Tools 12 Software Installation Guide for complete instructions.
Non-HD users, please install the latest compatible driver for your Avid interface.The HD driver may be found in the Driver Installers folder included in the 12.6 download. Pro Tools HDX/HD Native Mac users, be sure to install the matching HD Driver.Run these in addition to the Pro Tools installer. Virtual Instruments and Effects for Pro Tools 12 are installed by the First AIR Effects Bundle and First AIR Instruments Bundle (formerly a single Creative Collection Installer in PT11).Pro Tools 12.6 uses a single installer for both Pro Tools and Pro Tools HD, only the iLok authorization is different.Pro Tools 12.6 is a full installer (not an updater that requires a previous version installed).See the Support section of for assistance with iLok License Manager, your iLok account, etc.
This can be a single license or in a bundle.