I downloaded a psd mockup template and it doesn't work! The instructions do not work. help please

Here’s the link I purchased the psd from

I’ve tried dragging my png and a jpg image onto each layer and it doesn’t load up. Like it’s locked or something.
I have the latest photoshop and I have a 2022 imac. I’ve never had a problem with other psd files and click and drag/drop instructions before. Can someone please tell me if this link works for them or give me some advice on what could be going wrong? I don’t know how to contact the author either