It might take up to 12 hours for changes to show in your Google Calendar, according to Google support.
First, you need to create an export for the desired calendar as described in https://brizoit.atlassian.net/wiki/spaces/WTCDOCS/pages/3346633646.
Once a calendar export is created, copy the generated iCal URL.
Go to your Google calendar, and open its settings:
Click Add calendar and insert the generated URL:
The Work Time Tracking calendar events will be shown on Google calendar, and might look similarly to the next:
Once you've exported the Work Time Tracking calendar to the Google calendar, you can add notifications for the events created in the Work Time Tracking Calendar.