How to fix 'ARGUMENTS_NOT_ALLOWED' error Realm SDK for Kotlin?

I am using MongoDB to save data from my Android app which I am developing with Kotlin Jetpack Compose. I am using MongoClient to access the database and save the data, but when I try to insert a Document I get this error:

Error: ARGUMENTS_NOT_ALLOWED(realm::app::ServiceError:13)

This is my code where I login and try to insert a Document into MongoDB Cluster:

Realm.init(this)

    val appID : String = "my-app-id";
    app = App(
        AppConfiguration.Builder(appID)
        .build())

    app?.loginAsync(Credentials.emailPassword(email, password)) {
        if (it.isSuccess) {
            val user: User? = app?.currentUser()


            val client = user?.getMongoClient("mongodb-atlas")
            val db = client?.getDatabase("tracker")
            val coll = db?.getCollection("User")

            val doc = Document("_id", UUID.randomUUID().toString()).append("name", "Besart")
            coll?.insertOne(doc)?.getAsync {
                if(it.isSuccess){
                    ...
              }else{
                    Log.e("ERROR", "${it.error.errorCode}")
                    it.error.printStackTrace()
                }
            }
      } else {
          Log.e("ERROR", "Failed to log in. Error: ${it.error}")
      }
    }

This is Users schema I created from MongoDB UI:

{

 "title": "User",
  "properties": {
    "_id": {
      "bsonType": "objectId"
    },
    "name": {
      "bsonType": "string"
    }
  }
}