Action Required is the way ApiDrop asks you to perform an action necessary to unblock your products synchronization.
Its showed all the time you are going to sync a product from a new, not matched, category or attribute or brand.
Clicking on it will reveal what kind of error are blocking your product to be in sync.
Near each error there is a link named FIX IT that redirects you to the right section (usually is your platform's settings page).
Once there, you will notice that some tabs have a red bell icon on their left, that means that there are some matching actions that must be performed on that tab.
To better understand how matching works, please follow this guide
Once all errors (unmatched categories, attributes or brands are considered errors) have been fixed a green banner will appear on top of the page and error counters will show 0 under error column.
Now you can perform a new sync by clicking "Sync All Pending" button in "My Store" section.
If all errors have been correctly fixed, your sync will complete and products status will change from "Action Required" to "Ready".