Transitions i downloaded are showing up all black for the entire transition

Hey guys,

I downloaded some transitions and when I drag them over my clips. All it does is turn my screen black. The audio plays, but the transition doesn't. I reached out to the company who sent it and they said it's a resolution issue and sent me this poor quality youtube video to fix it. But it doesn't have volume or shows me anything. Wondering if anyone knew what the issue was?

Nowhere on the internet, I can find out to fix this!

Thanks