Remember, we can't see your screen, we can't know what you're actually clicking or doing while attempting to install the software. Unless you do something like record a screencast video to actually show what you're doing, the best we can do here is guess and offer suggestions based on previously resolved problems.
I can tell you the software absolutely does work on Windows 7 & 10. It also works fine on Windows 8 and even Windows XP, those almost everyone these days is using 7 or 10, so those are the 2 versions I use here for testing.
The most common mistake involves having 2 or more copies of the Arduino IDE software on your PC. In that scenario, it's very easy to install Teensyduino into one copy but then when you run a different copy, it's not installed. This can be especially problematic if you are running the Arduino software by clicking on .ino or other data files and Windows automatically chooses which copy to run.
But again, this is blind guesswork. I have no idea if you have more than 1 copy of Arduino. In fact, it's not even clear to me which version of Windows you use (though all versions from XP to 10 work).
Please, first focus on just getting the Teensyduino software installed into Arduino. If you're not seeing any Teensyduino version in Help > About, you haven't correctly installed Teensyduino into that copy of Arduino. No amount of selecting ports or messing with the hardware will help until you first get the software installed.