Just saw in the weekly ad:
Free 8x10 print with mobile app
use code FREESMILES.
Valid on mobile app only.
Expires 9/19 11:59 pm
One single image print per household, per account.
Ad clearly states only for use with the app but the fine print mentions website as well.
Edit: confirmed by the first two comments, it does NOT work for the website.
Definitely doesn't work at a kiosk in store.