first Error Msg:

Assets/Opsive/Shared/Game/Scheduler.cs(12,30): error CS0246: The type or namespace name 'SchedulerBase' could not be found. Are you missing an assembly reference?

first error code:

namespace Opsive.Shared.Game
{
    /// summary
    /// Wrapper for the shared Scheduler component.
    /// summary
    public class Scheduler : SchedulerBase
    {
    }
}

Second Error Msg:

Assets/Opsive/Shared/Game/ObjectPool.cs(12,31): error CS0246: The type or namespace name `ObjectPoolBase' could not be found. Are you missing an assembly reference?

Second error Code:

namespace Opsive.Shared.Game
{
    /// 
    /// Wrapper for the shared ObjectPool component.
    /// 
    public class ObjectPool : ObjectPoolBase
    {
    }
}

If you need more info comment and let me know what you may need.

_{Unity version is 2017/4.28f1 64bit}