On my main app page, I select "test your app" (screenshot 1), and then "install app" (screenshot 2). see 2 screenshots below. It then correctly transfers to the url specified in the "App URL" input box in the "App Setup" page.
Following the instructions in the docs linked above, I then change the url using window.location.href = to the url specified in the docs with the correct query params. I.e: