I have literally been waiting for 15 years to beat police quest 4. My copy that I had when I was younger was glitched. Now, here I am, minutes from beating the game, and I can't get the dog to even appear in Griffith Park... Any ideas?

Hard to say. You probably missed something that triggers it. I'd trace the steps of this day in a walkthrough up to the point where you're stuck at the moment. Just be careful to not reading further, since there's nothing worse than spoilers in adventure games ;-)

You have to get a rope. You have to go to the alley in southern L.A. and there's a rope in one of the boxes

I have the same issue on my physical copy, I did all I could in the walkthrough, and I can't get the dog to appear in the park. Am I just screwed?