How to use mongo in Unity. The Driver. The GridFS. DLL file

How to use in Unity mongo. Driver. The GridFS. DLL files, why an error

unity error:TypeLoadException: Could not resolve type with token 01000035 (from typeref, class/assembly MongoDB.Driver.Linq.LinqProvider, MongoDB.Driver, Version=2.26.0.0, Culture=neutral, PublicKeyToken=null)
MongoDB.Driver.GridFS.GridFSBucket.Find (MongoDB.Driver.FilterDefinition`1[TDocument] filter, MongoDB.Driver.GridFS.GridFSFindOptions options, System.Threading.CancellationToken cancellationToken) (at <6df8141e3c9d4f82b6015feef0f32cba>:0)
GridFSManager.Start () (at Assets/GridFSManager.cs:23)