I am using Redmi phone

Step 1: Tap on the "Settings" 

Step 2: Goto "Notifications & status bar" menu

Step 3: Now tap on "App notifications" 

Step 4: Now find "Skooly" app, on the list of apps and tap on it

Step 5: Now at the top, there will be "Show notifications", slide the toggle to enable notifications

Now you will receive notifications from "Skooly" app

If you cant find your settings here, please find your device in the following list of Xiaomi phones