GMod Beta Workshop

I have a map that I made about a year ago, and it’s on the Garry’s Mod Beta workshop.
I want this map, but I no longer have GMod Beta in my library for some reason

Here’s the link: http://steamcommunity.com/sharedfiles/filedetails/?id=96349589

How can I get it?

"Sorry!
An error was encountered while processing your request:

The item is either marked as hidden or you do not have permission to view it.

Here’s a link to the Steam Community home page."

It’s public. I guess I am the only one that can see it?

Appearently.

I get exactly the same error.

What can I do?

If you don’t still have the map file, I don’t think you can get it.