So my scan has showed up in Evernote Web now. It turns out that even if I create a new note in Evernote Web, it doesn't show up in the list of notes. It looks like there's a long delay with new notes showing up in Evernote Web for some reason.
I scanned two documents with Scannable, then uploaded to Evernote from the Scannable app. If I open Evernote on my iPhone, I can see the document, but I cannot find the document in Evernote Web. Even when I search, nothing comes up.