With Windows 10 x64, the setup is blocked by:
HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\NET Framework Setup\NDP\v4\Full\Version
HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\NET Framework Setup\NDP\v4\Client\Version
Change both values temporarily to 4.0.30319 and the setup will let you continue. Make sure you edit the registry with elevated privileges, otherwise you will not be allowed to change the values.