Ultimate++ Windows releases
Windows release a simple archive .7z archive. Unpack to directory of your preference, then just run theide.exe (or theide32.exe if you have 32-bit windows). U++ does not write anything to registry or outside its directory.
U++ comes in two variants:
upp-mingw contains mingw64 compiler system for out of the box operation
upp-win comes without compiler/SDK,
Both variants are able (on first install, when installation is moved or on demand - menu Setup/Instant setup) to detect and use Miscrosoft Windows SDK and C++ compiler, either 2017 or 2015 version. The most convenient way is to install Visual Studio Build Tools. Please check this blog entry about this option. When installing, make sure that support for Win32 applications is installed as well.