I forgot my new password for this store and tried a couple. To do this in the AppStore, you need to click on "buy", and I chose Adobe Elements. After I input the right password and hit OK, the program started downloading...
From
Mac App Store: How to browse and purchase from the Mac App Store:
When you find an app that you like, click Buy (you may be asked to sign in with your Apple ID)....When you click Buy, the app will begin downloading automatically...[emphasis added]
I think the point is to make purchasing apps as easy as possible.
