Hover Your Phone Camera Over Your Document
Once you hit "Scan Documents," a camera screen will appear. Point your phone camera at your document. It should automatically locate the document and highlight it in yellow (this can sometimes take a few tries at first — don't worry!). Once the document you want to scan is highlighted completely in yellow, it will automatically capture the document image or you can also tap the bottom white icon to do this. In my case, my document was easily detected and automatically scanned and saved.