iMovie Not Downloading!

Two weeks ago, my laptop said that my iMovie was downloaded under a different apple ID and it could not update. So thinking I could just re-download it since it came free with my 13 inch Mac Air, it would work. I had to repurchase the newest version of iMovie for $16.99. Tried downloading the new version since July 17, 2015 and it just says "waiting" and goes no further. Someone HELP please! SOS! Anything will help! I'm a YouTuber and I need this App to work 😟

Thanks,

K.S.