CloudWatch: Posted custom metric data successfully, but can't find the data

Using this code: https://github.com/awsdocs/aws-doc-sdk-examples/blob/main/javav2/example_code/cloudwatch/src/main/java/com/example/cloudwatch/PutMetricAlarm.java

I was able to put a custom metric data successfully:

Successfully put data point 123.000000

However, I'm unable to find the data, cloudwatch metric screenshot: https://www.screencast.com/t/RI3pq8KWmww

I've double checked the region

My scala code:

object TestClass extends App {
  PutMetricData.main(123)
}

object PutMetricData {
  def main(args: Integer): Unit = {
    val dataPoint = args.toDouble
    val region = Region.US_WEST_2
    val cw = CloudWatchClient.builder.region(region).credentialsProvider(ProfileCredentialsProvider.create).build
    putMetData(cw, dataPoint)
    cw.close()
  }

  def putMetData(cw: CloudWatchClient, dataPoint: Double): Unit = {
    try {
      val time = ZonedDateTime.now(ZoneOffset.UTC).format(DateTimeFormatter.ISO_INSTANT)
      val instant = Instant.parse(time)
      val datum = MetricDatum.builder.metricName("PAGES_VISITED1").unit(StandardUnit.NONE).value(dataPoint).timestamp(instant).build
      val request = PutMetricDataRequest.builder.namespace("SITE/TRAFFIC1").metricData(datum).build
      cw.putMetricData(request)
    } catch {
      case e: CloudWatchException =>
      System.err.println(e.awsErrorDetails.errorMessage)
      System.exit(1)
    }
    System.out.printf("Successfully put data point %f", dataPoint)
  }
}

Context: I'm new to AWS, I didn't create any metricNames or nameSpace in AWS, I'm assuming I can change the MetricName & namespace in the code and it'll create it in AWS. Do I have to specify an existing namespace or metricName?