When prospects register via a Marketing Cloud Account Engagement form, they will still receive GoToWebinar's reminder and registration emails. This is because Marketing Cloud Account Engagement integrates with GoToWebinar and automatically registers prospects for the webinar when they fill out the form. Marketing Cloud Account Engagement also syncs the attendance and other webinar data with the prospect records. However, Marketing Cloud Account Engagement does not send the webinar emails, which are handled by GoToWebinar.