I just couldn’t find where to download the installer for LightRoom v.5.7.1 online.
The only sites seemed to be dodgy. Adobe only seems to be offering v4 or v6+ and CC versions.
So here we go Download Adobe LightRoom v.5.7.1 Windows Installer from an official Adobe web site.
http://ftp.adobe.com/pub/adobe/legacy/lightroom/win/5.x/Lightroom_5_LS11_win_5_7_1.exe