1.if you never run addsubmodule.bat ,you should run once
run addsubmodule.bat
2.then you cd greatestworks-client\Assets\Scripts\Network\proto
run gen_csharp.bat
3.also you need add Google.Api.CommonProtos
https://www.nuget.org/packages/Google.Api.CommonProtos/#versions-body-tab
too -> nuget package manager -> ~console
Install-Package Google.Api.CommonProtos -Version 2.6.0