~/Downloads$ unzip signal-desktop-mac-1.24.1.zip
Archive:  signal-desktop-mac-1.24.1.zip
  End-of-central-directory signature not found.  Either this file is not
  a zipfile, or it constitutes one disk of a multi-part archive.  In the
  latter case the central directory and zipfile comment will be found on
  the last disk(s) of this archive.
unzip:  cannot find zipfile directory in one of signal-desktop-mac-1.24.1.zip or
        signal-desktop-mac-1.24.1.zip.zip, and cannot find signal-desktop-mac-1.24.1.zip.ZIP, period.