If not then your staff need to share their calendar to you with the permissions:
Make Changes and Manage Sharing

see pic....

Log into Google Calendars with the account that you will use with Better Scheduling. Then on the left-hand side menu go to Other calendars > add other co-workers calendar


You can assign different colours to the calendars to make them easily recognisable of who they belong to if you click the drop-down next to the staff calendar overlay > Choose colour

Resume setup of Better Scheduling for WorkflowMax