Using Juce 7 and Visual Studio 2022, I get when starting the error message “Unable to start the progam… is not a valid Win32 application”. I should see the Hello World screen. What now?
Did you try building the whole Visual Studio solution first? (Control+Shift+B is the default shortcut for that.)
Are you actually trying to run an application or are you trying to run a plugin? In the second case, be aware that an audio plugin is no application that can run on its own but always needs a plugin host application that loads it.