henryWIJAYA Here is the information I found. It says to include third-party SDKs.
Google mediation supports over 30 third-party ad networks. Integrating mediation requires changes in these places:
Third-party ad network UI - Sign up for the third-party ad network and create a placement in their front end.
AdMob UI - Update your ad unit's mediation settings to include the ad network. It is also recommended that you set up ad network optimization for ad networks that support it.
App code - Update your app to include the third-party ad network's SDK, and an adapter library that communicates between Google and the third-party ad network to request and serve ads.