Unity Playworks Plugin API
Message
You are not using the Playworks Plugin API call which are required for some ad networks.
Explanation
Some ad network require to have API calls, else they will reject your playable. Such as GameEnded() API call. To make it easier for the developer, Playworks Plugin has integrated all the calls from each ad network into a single API call.
Steps to fix
Please implement the required API calls: Luna.Unity.LifeCycle.GameEnded();, more information here. And Luna.Unity.Playable.InstallFullGame();, more information here.