You can watch every virtual tour on your smartphone by opening it in a browser of your choice.
Clicking the icon in the upper-left will open the menu with the following options:
Move the image by swiping with your fingers.
Use the internal gyroscope of your smartphone to move the viewer by moving your phone around.
Please note: Not every smartphone has a gyroscope.
Walkthrough the viewer like you are in the room itself, more information about the virtual reality option can be found here.
What if this doesn't work?
Make sure you installed all the latest updates for your phone.