Design Download [upd] Mac — Autodesk 123d

Autodesk 123D Design for Mac is no longer officially supported or available for direct download from Autodesk, as the software was retired in 2017 to make way for more advanced tools like Fusion 360 Status Report: Autodesk 123D Design for Mac Availability Status Retired/Discontinued

123D Design was officially discontinued by Autodesk in early 2017 and is no longer available for direct download from their official website Autodesk 123d Design Download Mac

Autodesk effectively replaced 123D Design with Fusion 360. Autodesk 123D Design for Mac is no longer

You have hundreds of old .123dx files from years ago. You need to edit them, but you cannot run 123D Design. but you cannot run 123D Design.