Also, consider that Pro Tools 12 is a 32-bit application? No, Pro Tools 12.8 onwards support 64-bit on Mac. The transition from 32-bit was around 2016 with Pro Tools 12.6. So Pro Tools 12.8.3 should be fine.
Before downloading, ensure your Mac hardware and OS are compatible: pro tools 1283 download mac top
Proceed through the installation screens, agreeing to the terms and entering your Mac's administrator password when prompted. Also, consider that Pro Tools 12 is a 32-bit application
Pro Tools 12.8.3, released on December 19, 2017, was a pivotal update designed primarily to support the then-new and introduce compatibility for macOS High Sierra (10.13.2) . It is known for significant playback performance improvements and is the final version to support Windows 7 . Key Compatibility and Requirements released on December 19