Check notification permission. iOS Settings, Notifications, Aura, Allow Notifications on.
Check your Focus modes. This is the most common cause. If a Focus mode is running, Aura may be silently filtered even though permission is granted. Open Settings, Focus, pick the mode, and add Aura to its allowed apps.
Check the routine itself. Open the habit and its routine sheet, and confirm the time and days are what you think. A routine set for weekdays won't fire on Sunday.
Check Scheduled Summary. If you use it, Aura's reminders may be held and delivered in a batch rather than at the moment. Settings, Notifications, Scheduled Summary, and remove Aura from it.