Guides Studio has not started

If this message stays on screen:

• You opened index.html directly from a folder? Browsers cannot run the app that way. On Windows, double-click GuidesStudio.exe in the same folder.
• Or open https://guides.henning.rodeo in your browser. After one visit it also works without internet.
• Still blank? Use a current Edge, Chrome or Safari and make sure JavaScript is allowed.