Found the solution:
When downloading, it was adding “GZ” suffix to the download.
When I Removed that, the icon changed (I guess due to OS identifying the file)
Double clicked and BINGO, files are installed.
Which… doesn’t matter now as I made my own stencil.
Maybe I’ll share them?
Maybe adding the extra “GZ” broke the file association in MacOS; it didn’t know what to do with a “.GZGZ” file. The OS is pretty good about determining what to do with different file types. Most of the time, the file type (extension) is hidden and handled automatically. If you used a PC for a while, this can cause a little confusion since most show the extension.
Good to have too many stencils in the town than too few!