Viewer
Mac
storyboard-viewer-mac.dmg contains StoryboardViewer. You can drag and drop to copy it to Application Folder.
Mac Setting > Securty & Privacy. App Store and identified developers should be enabled.
Win
Uncompress the dowloaded storyboard-viewer_win.zip and you find setup.exe
click setup.exe. It maybe show a Security Warning, please continute by clicking Run button.