To enable push notifications on the app make sure Push Notifications are enabled under Walla App settings and Allow Notifications is enabled for the Walla App under your phone's settings.
Enable Push Notifications on the Walla App
Within the Walla App select Account
Choose Notification Settings
Turn on the toggle for Push Notifications
Select Save
Enable Push Notifications on Your Phone
Select Settings
Choose Notifications
Select the Walla App
Turn on the toggle to Allow Notifications