An email alert (on the email associated to your ShareGate Overcast account) is sent by ShareGate Overcast only when an anomaly is detected.
If an anomaly is detected, you will receive an email at 7:00 AM EST. There is no way to set another time for alerts.
If you want to activate the email notifications, open your CostHub, click on the menu button in the top-right corner, and select Anomaly alerts.
In the Anomaly alerts screen check Receive email notifications.