To activate the VR mode, click on the mask icon at the bottom-right of the screen, then put on your helmet.
To exit from the VR mode,
must aim for the « Mask » icon, to the right of the toolbar that appears looking up.
To play the animation, aim for the « Play » button looking up.
To switch from one player to another, aim for the player during 2s, until the yellow circle is complete.
Manual here