Currently, we don't have a system in place for notifying approvers when teammates assign social posts as "Need Approval." The best way to monitor for posts that need approval is to set up your daily activity digest. This will give you an understanding of your team's activity each day, including when your teammates submit social posts for approval or approve or reject posts in the dashboard.
To set up your activity digest, click on your account icon (top righthand corner of your dashboard), and select "Account Settings". Once you're in Account Settings, select Reports. To receive daily reports, click "Daily" under your dashboard name.
You'll receive an activity digest email each day, bright and early (4:00AM ET), so that you can plan strategically for the day ahead.
Your second option will be to have your team take advantage of the task management system (Planning --> Tasks). Teammates who need posts approved can assign you a task to review desired "Need Approval" posts. You'll receive emails anytime someone assigns a task to you.