(if not already):

The tool calculates ductwork specifications by analyzing airflow (CFM), pressure loss, and air velocity. Sizing Methods : Supports both the Equal Friction Method (standard) and Equal Velocity Method Air Properties

The original was a Windows-based lightweight executable (.exe). To use similar functionality on a modern Mac, you have three primary options:

Use software like Parallels Desktop, VMware Fusion, or VirtualBox to run the original Windows-based McQuay software.

While the original McQuay Duct Sizer software—now maintained by Daikin Applied

If you are loyal to the classic McQuay interface, you can use compatibility layers or virtualization to run the Windows program on your Mac. 🍷 Use Wine or Wineskin (Best for Intel & Apple Silicon)