open your mac terminal type following:
cat ~/Library/Logs/Adobe_ADMLogs/Adobe_GDE.log
this will output Adobe's installer log, it tells you the actual flash player installer it downloaded, try to find a line like following:
01/09/16 10:01:54:482 | [INFO] | | | | | | | 76833 | The file to be downloaded is http://fpdownload.adobe.com/pub/flashplayer/pdc/20.0.0.267/install_flash_player_osx.dmg
now you know where to download the file, still in the same terminal window, use wget to download the dmg file.
wget http://fpdownload.adobe.com/pub/flashplayer/pdc/20.0.0.267/install_flash_player_osx.dmg
it will download the dmg file in your current folder, most likely your home folder, now use Finder to navigate to the dmg file and launch it and click the "Install Adobe Flash Player" icon in the mounted disk image.
good luck!
