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#11
Double clicking on the zip file here opens the zip file which contains a single file Old Calculator for Windows 10.exe which is the installer.
This installs the file Calc1.exe to this location C:\Windows\System32\
The temp location is a Red herring in that it is used only to create the exe in the right location
If you create a shortcut to C:\Windows\System32\ Calc1.exe this should invoke the old calculator