error in zombiegameplay

Hi, yesterday I downloaded garry’s mod. and everything went just fine. until I wanted to play a multiplayer game. first download it many folders, tools, etc. that will be normal. but it took so long that I do not like it … So this morning I wanted to play zombies download it then. after I had downloaded, I came into the game liking. I saw all kinds of errors in red. hear this so?

Red errors = Missing content.