It's not about the installer... I have the Heroes TE files completely downloaded and installed as an archive... I didn't install anything myself - neither TE, nor anything else... Okay, I'll try following Natasha's advice...
Well, downloading TE and trying to install it will really only take 5 minutes. And it's very simple to unpack it into the update folder and run update.exe. It's worth a try, although following Natasha's suggestion should also work!