ReadingUsers.cs

public async Task<List<User>> GetAllUsers()
{
    return await _usersCollection.Find(new BsonDocument()).ToListAsync();
}

public async Task<List<User>> GetUsersByField(string fieldName, string fieldValue)
{
    var filter = Builders<User>.Filter.Eq(fieldName, fieldValue);
    var result = await _usersCollection.Find(filter).ToListAsync();

    return result;
}

public async Task<List<User>> GetUsers(int startingFrom, int count)
{
    var result = await _usersCollection.Find(new BsonDocument())
                                       .Skip(startingFrom)
                                       .Limit(count)
                                       .ToListAsync();

    return result;
}