Paid Keywords are the keywords for which the app you're tracking has paid and ranked for within the past 90 days.
If you add some competitors, you will be able to spy on their own Paid Keywords as well.
Shared Keywords are the keywords for which both you and your competitor(s) have bid on.
This feature is very useful to determine your own strategy and understand the competition. Great source of inspiration for your organic keywords as well
Check out our complete Search Ads Intelligence Dashboard.