Yes. The Mill needs the Mill app and uses the internet upon pairing and setup to enable its internal clock so it can keep an automated schedule.
After setup, you can operate it without Wi-Fi and without the app by starting manual cycles via the lid button. Please note that without consistent Wi-Fi connectivity, you won't be able to access some of the features like automatic scheduling, and email impact reports with details on how much food you've added over time, etc. and the team may have difficulty assisting with backend troubleshooting (if needed).