Sign in to the PlayStation Network account that made the purchase and try the download again.
Check your connection and resolve any problems and check that your firewall settings are not stopping the download.
If you are downloading content to this PlayStation 4 system from your PlayStation Network account for the first time, you may need to activate the system as your Primary system. Make sure by activating it and check that you have not reached the device activation limit before attempting the download.
Check the size of the file you are downloading on PlayStation Store and make sure there is enough spare HDD by checking system storage
Check here for the most recent system software update, check the system software version on your PS4 by going to [Settings] > [System Software Update] and download the update if needed.
Occasionally your connection may be interrupted if you are playing while waiting for the download. Stop play until the download is complete.
You may be experiencing a less general issue that needs to be fixed in a particular way. Select the problem from the list below to go to more ways to fix it.