Short answer: First send a test from Profile > Settings > Notifications > Send Test Notification. If the test does not appear, your phone is blocking Dose Track. If it does, check that the medication has a reminder time and that Scheduled dose reminders is on.
Open Dose Track once after changing phone settings, a time zone or the date. The app plans its reminders again each time it starts. Force-closing the app on Android can stop pending reminders until you open it again.
Still stuck? Email hello@dosetrack.app with your phone model and system version, or ask in the community.