SketchUp for Web with the SketchUp Go works only in the browser and has NO desktop version. There is also nothing to download in this case, so using the software is entirely online.
Start SketchUp for Web
Open your browser (preferably Google Chrome) and open the page app.sketchup.com.
On the next screen, enter your email address and click “Next.”
On the next screen, enter your password and SketchUp for Web will launch.