It does mean that there are too many people on the site trying to download designs at the same time. Just try again later when there are fewer people on.
It usually comes up when the site is busy and gets very slow and you can't get a connection. Keep trying.
Came up for me also but on the bug designs. Sorry but I hav en o idea what it means unless there are many cuties trying at the same time. Just guessing here but I feel sure someone will be able to answer. I'd like to know too. *4U