I put this in here because it’s happening with Garry’s mod too but every single game I try to install (new computer) just says “download starting” and never starts. Someone, please help! Sorry I put it in the Garry’s Mod discussion on accident.
I usually press Launch Game, then it starts downloading and opens a window on Update Status. And shows how long is left.
The server you tried to download it from is too busy. If it keeps doing that over and over, go into Steam Settings and choose a different server