I am using Lenovo K8 Note (Android 7.0)

Step 1: Go to "Settings"

Step 2: Tap on "Notifications" 

Step 3: In the list of apps, tap on "Skooly"

Step 4: Now tap on "Notifications"

Step 5: Make sure that all the three toggles i.e "Block all", "Show silently", and "Override Do not Disturb"are "OFF"