Hey,
I just had to reinstall Windows, so I also had to reinstall the FSDT Installer. I've never had any issues with it before, but now, when I try to launch the installer, I get a setup error, as you can see in the screenshot. I've already excluded the Addon Manager folder in Windows Defender, and I did the same for the Installer and Live Update executables. My internet connection is fine, since I can download other files without any problems. Does anyone know what else I can try?