The usual causes, in order:
- Notifications are off for the app. On iPhone: Settings → Notifications → Okeedoo → Allow Notifications.
- No moment chosen, or it is set to Not at all. Pick one on your child's page.
- You already tapped today. The daily note deliberately skips days you have already used the board.
- A Focus mode is silencing it. Check Settings → Focus.
- The app was reinstalled. Open it once and tap the test button again so it can re-register.
Notifications need the iPhone app. On the website alone, the same messages come to you by email.