How do I get this ID the WEB IDE is asking for? I downloaded the cLI and it won't stay open. Why can't the device ID just be read from the USB connection?
Where is the Web IDE asking you for a Device ID? It should only ask if you are adding a device, but that should not be necessary.
You should set up your device using https://setup.particle.io/ which will set up your device and add it to your account so it automatically appears in the device list without needing the device ID.
If you really want to know your device ID, you can generally get it by USB, there are a dozen ways of finding it in finding your Device ID.
How are you launching the Particle CLI? Once you install it, you run it by using the particle command from Terminal (Mac and Linux) or Command Prompt (Windows).