How to insert image to a mask layer?

[Henry]

Hello everyone,

I'm trying to create a book mockup. The mockup template is a PSD file which opens fine in Gimp. The cover image needs to be pasted into a layer with a mask.

I found a tutorial video which shows this step very easily in Photoshop: https://youtu.be/QqrMKLwmxMs?t=195

I wonder if this step is also possible with Gimp?

Thanks