Dear Preeti,
I have come up with a solution to run STRUCTURE on M1/M2/M3/etc ARM-based Macs:
There is a program for Macs called UTM that can emulate an x86-based Ubuntu Linux machine, and STRUCTURE can be run under Ubuntu Linux.
(To those familiar with the technical capabilities of UTM: I know UTM can also be used to *virtualize* ARM-based Ubuntu Linux, but STRUCTURE requires i386 libraries that I assume do not work under ARM-based Ubuntu.)
I actually have developed a pre-configured Ubuntu Linux virtual machine that you can emulate on your Mac that already has STRUCTURE pre-installed. All you have to do is:
1) Download and install UTM on your Mac. Instructions here (from 0:00 - 5:37):
Be sure to stop at the 5:37 mark.
2) Download my pre-configured virtual machine:
3) Hook my pre-configured virtual machine up to the UTM software on your computer:
4) Run STRUCTURE:
PS: As a bonus, here's a tutorial I made to show how to make publication-readily figures from the STRUCTURE output:
I hope this helps you and the rest of the community!
-Joshua Banta