Shouldn’t there be two image/video comps for transition animations?

Each transition animation contains a single Image/Video comp. This comp represents the second half of the transition. To complete the animation, render the transition comp with an Alpha channel. You can find instructions on how to do this in the ‘Read Me’ file included with your template.

Once rendered, the final file will transition from black to the Image/Video you selected. The black is actually transparent and if you drop this rendered clip on top of another clip inside of Premiere or Final Cut, it’ll complete the transition animation.