how to select 2 or more photos in Photo Bin to use in Photomerge

I am using a MacBook Air running MacOs 12.01 and Photoshop Elements Organizer 2021. I am trying to merge two contact sheets of which I have images. No matter what I do, I cannot select both images in the PhotoBin using the suggested Command/Click command. Can anyone halp me? Previous posts on this topic deal with older versions of Organizer and MacOS.