Silly question… But how do you add a photo to an album? I know its a simple question, but I assumed you right clicked it and click add to album like any other photo management application… Then I assumed it was in the sidebar, but I didn’t see an option there either…
The Photos app interprets your directory structure as an album, so you need to move your images to different sub directories to get it organized. The function you’re looking for doesn’t exist in Nextcloud yet.