in the right bottom corner you will find the switch camera icon, click it to switch views until u get the orbit camera, then u can look around, click on the floor to mark your destination, then click the marker to walk, or use keyboard, if u are using mobile or tablet u can touch and hold screen and swipe to move.
To help debugging or developing your own version of threeverse use resources saver chrome extension to get all assets, or download source code.
Make sure you check the “Include all assets by XHR requests (require page reload).” checkbox. Do not check “Beautify” checkbox, this will alter the html and css.