I believe this is the problem i once had. You need to quit garry's mod, go and manually download the map from workshop (bhop maps are rarely there) or download it from the internet. Then you drop the .bsp file to your garrys mod map folder, start garrys mod and you should be able to join

I believe this is the problem i once had. You need to quit garry's mod, go and manually download the map from workshop (bhop maps are rarely there) or download it from the internet. Then you drop the .bsp file to your garrys mod map folder, start garrys mod and you should be able to join :)