How to export from a photoshop template

Hello. I downloaded a photoshop template for 15 instagram posts. Each post is labeled in the template and contains about 5 layers, seperate from the rest of the posts, like each post is a different canvas.

I expected that I could simply copy each post to a new file and save as png, or simply export to png. Yet these functions don't seem to work, all I get is a 1080x1080 px square of white instead of the post. This is my first time using a psdt file, so how

doI get just one of the 15 posts out of the template?  I need one image for each of the posts on the template.

Thanks, 

Cori