Another option for downloading your app is to create an .aia file, which is generally used when distributing the project source to others for collaboration.
This enables someone else to upload your app into his or her own App Inventor account and then make additional adjustments.
Alternatively, someone else could remix the app by making improvements or other adjustments to your original concept. This method also is useful if you are collaborating with others, as a way to problem-solve or provide examples of how to create a particular feature. As you build more complex apps, you might find more opportunities to work with others and share ideas about what types of strategies work best with App Inventor.
To download your app ...