The latest version of Cymatic (released this weekend) requires a Windows component called Microsoft .NET Framework version 4.6.2 (or later versions of that).
That component is not compatible with Windows Vista or Windows XP. So Cymatic now requires at least Windows 7 SP1, Windows 8, Windows 8.1, Windows 10 or later (or server versions from Windows 2008 onwards).
If your version of Windows has an earlier version of the Microsoft .NET Framework installed, then Cymatic will direct you to install version 4.6.2. Or you can go here to get it directly:
Microsoft .NET Framework version 4.6.2 (Web Installer)