Can you help me with my problem in the App Store, it won’t allow me to download a app

I need help with something that had happened. The fortnite app had been released and I was invited to play it. I went to the link and it took me to the App Store and that is where I downloaded it. The problem is that it was downloading halfway then it stopped and then it disappeared. It said that it wasn’t able to download, I went to do it again and again but now it just won’t move an inch. Can you please help me