Jwt Builder and HMACSHA256Algorithm not working

Hi Friends,

Getting errors at Jwt Builder and HMACSHA256Algorithm does not exist.I tried to install JWT  through nuget and package console in our .net core 2.1 project but not installing.

 string apiKey = "32a4ef";
        string secretKey = "qloDZF";
        int currtime = 163068;

        var payload = new Dictionary<string, object>
        {
            { "iss", apiKey },
            { "iat", currtime },
            { "jti", Guid.NewGuid().ToString() }
        };

        try
        {
            string token = new JwtBuilder()
                .WithAlgorithm(new HMACSHA256Algorithm()) // symmetric
                .WithSecret(secretKey)
                .AddClaims(payload)
                .Build();

            Console.WriteLine(token);
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.Message);
          
        }

Is there any other way to get the token similar to this code.