Kubity respects the laws of physics, so if there is a wall or a closed door in your model you cannot walk through it in normal ‘walk mode’. However, you can walk through walls and closed doors in Virtual Reality using your phone + Google Cardboard with "Gaze & Go".
How to use Gaze & Go
If you’re in First Person POV on the computer, you can "teleport" through doors by dragging and dropping the person icon where you want to go. This will allow you to be unconstrained by the physical properties of your model (closed doors, walls, etc.)