Miles's Journey to the Spider-Man Universe

Miles's dad is going to die in like two days if he doesn't get back. And then it's basically just a chase. But I think I know where you may have gotten confused. In the first movie, Miles is bitten from a spider that is not from his universe. There's no Spider-Man in that other world. When Miles jumps into that basic like portal, it sends him back to the world where that Spider was from.