Apple Store - Mavericks/Yosemite Stuck at "Downloading" and actually does NOT continue to download?
Look at the Launchpad icon in the Dock.
If it's downloading there will be a thermometer [which I've since been informed is actually called a determinate progress bar] under it showing progress. 

Bear in mind the download might be as much as 6GB, so 5 minutes isn't really much at all unless you have a really fast connection.



If you rebooted, dropping the connection, then you might have to poke at it a bit to get it going again. It ought to auto-resume, but sometimes gets stuck.
If it did, click Launchpad, find the partial download icon, then hold  Opt ⌥  &amp; click the X in the top left corner.
Go back to Purchased &amp; start over.