Once you’ve made it to the end of the first rooftop section (after about 250 Meters) the character will approach a zip line and use it to zip down to the streets and into the Shellraiser. This will happen automatically once you reach this point. If you would like to get to the streets more quickly, you can purchase a ninja smoke bomb in the shop for coins and use this gadget in-gameto jump forward to the next section immediately.