You can automate invitation emails on roster sync when populating your form with a roster. Navigate to the Supervisors & Settings tab in the Form Manager and toggle the corresponding option.
Once toggled ON, whenever a new response entry is rostered to the form, the respondent will automatically receive an email invitation to complete a response.
If this option is disabled, once rostered, you will see a yellow bar at the top of your Form Manager that indicates how many emails are ready to be manually sent.
Please note that when you automate the email invitations, you will NOT be able to review the email message before sending them.