Hello there, AlphaSounds.
The following Knowledge Base article provides some good pointers for issues with the Mac App Store:
Of particular note:
If downloading an app is interrupted
Once an Internet connection is reestablished, your purchased downloads should automatically restart. The Mac App Store may alert you that there was an issue with the download and ask if you'd like to restart the download(s). Confirming will restart all pending downloads. For more information on this topic, see Mac App Store: How to resume interrupted downloads.
Note: The download time will vary according to the file's size and your Internet connection speed. Refer to this article about iTunes Store purchases for more information about download times for large files.
- You can find additional information by choosing Help > App Store Help from within the application.
- Additional articles and support resources for the Mac App Store are available here.
Thanks for reaching out to Apple Support Communities.
I think Apple should provide a DVD install or a SHA 256 hash check for confirming the Operating system is donwloaded and validated. Several people have had problems downloading the Operating system and more important if you download something as critical as the Operating system you should be able to confirm the download was performed succesfully.
Other Operating systems have mehtods of validating like Windows and Ubuntu. Why does Apple not allow for say a SHA 256 hash check?