The download for WMF 5.1 for down level operating systems is now available:
WMF 5.1 can be installed on Windows 7 and 8.1 plus Windows Server 2008 R2, 2012, 2012 R2
Windows 10 and Server 2016 already have PowerShell 5.1 and don’t need this install.
if installing on Windows 7 or Server 2008 R2 the installation process has changed – READ THE RELEASE NOTES OR BE PREPARED FOR A LOT OF EXTRA EFFORT
ScriptPosse 