as you mentioned
3.5 Downloading your application
Users typically save and back up their applications locally, often with a source control management system like GitHub.
Should you need a copy of the data or R code that was last deployed, you can download a zip file that contains the full bundle by clicking on the Download button next to the Bundle label on the Application View page in the shinyapps.io dashboard.
but when i am trying to download it give me tar file. when extracting tar i did not find any content, i found just one file without extension.
this is not downloading in zip