How to upload images to a specific album in Google Photos:
- Create the album. You have to choose an existing photo to create it.
- Drag and drop the photos you want to upload onto the album you’ve created.
Despite years of customer requests you still can’t select a folder and upload it into an album.
I’ve read that if you work with full res (not reduced) images in Google Drive you can organize them in folders and turn those folders into albums in Google Photos. These count against storage costs. I have not tested this.