Technicadragon3

Hi everyone, I'm completely new in the mod stuff at cities skylines. I see that the game is cheaper at other stores in comparison With the price on steam. But... if i buy it in a local or online store, can i then still get these mods without have the need download it illegal of something and get a virus on my pc?(can you still get them by steam?) Because these buildings and stuff are insanely cool. I never played it but i will buy it if i know where its the smartest move, i hope someone can help me make the best desission I appreciate your time,