Most likely you have the map, it just hasnt been unzipped.

Go to your cstrike folder by going to steam >> ganes >> CSS >> right cligh properties >> local files >> browse local files >> cstrike

Then find the maps folder within there in downloads, find gg_fy_funtimes.bsp.bz2 and unzip it to be gg_fy_funtimes.bsp

Alterntively just delete the .bz2 version