Update: Looks like everything is back to normal.
If you’re trying to download or update an app from the App Store right now, you might be greeted with the unpleasant message that “this feature is temporarily unavailable,” inviting you to try again later. If you are experiencing this issue, know that you aren’t the only one as many have been reporting the exact same problem for over an hour now.
Apple System Status doesn’t report any outage at this time, but we can only imagine that will change soon.
At this point, our advice is to just sit patiently and wait for Apple to fix this issue on their end.