The following errors can occur if you are using a different Google Play services version package than the one that is provided with the Mediation package. The Unity Editor expects a .dll file to have the same name as its assembly, but it is not the case with these packages. Although we recommend that you use the package that is included with Mediation, you can patch this issue by renaming the specified .dll and then removing the version from its name. In the preceding example, rename Google.IOSResolver_v1.2.166.dll to Google.IOSResolver.dll.
Assembly 'Assets/ExternalDependencyManager/Editor/Google.IOSResolver_v1.2.166.dll' will not be loaded due to errors:
Assembly name 'Google.IOSResolver' does not match file name 'Google.IOSResolver_v1.2.166'
For more information, see the Unity Mediation documentation.