When you take the first photo of your receipt, it will automatically open the receipt editing screen. On this screen you should see a preview of that photo you just took at the top, and a little plus + sign icon on that photo. If you tap the plus sign you’ll be taken to a full view of the photo where you’ll then see “page” in the bottom left of the screen.
Tap on “page” to upload additional photos of that document or long receipt!