I have been struggling to find out the error in writing the principal correctly. From Aws console I am trying AWS polly and want to save the output to s3 bucket. The IAM user is created with the following permissions:

{
    "AttachedPolicies": [
        {
            "PolicyName": "AdministratorAccess",
            "PolicyArn": "arn:aws:iam::aws:policy/AdministratorAccess"
        },
        {
            "PolicyName": "AmazonPollyFullAccess",
            "PolicyArn": "arn:aws:iam::aws:policy/AmazonPollyFullAccess"
        },
        {
            "PolicyName": "AmazonS3FullAccess",
            "PolicyArn": "arn:aws:iam::aws:policy/AmazonS3FullAccess"
        }
    ]
}

On S3 Bucket permission tab I trying to add the given policy:

{
  "Id": "Policy1720073611620",
  "Version": "2012-10-17",
  "Statement": [
    {
      "Sid": "Stmt1720071547531",
      "Action": "s3:*",
      "Effect": "Allow",
      "Resource": "arn:aws:s3:::mytest2-text-to-speech/*",
      "Principal": {
        "AWS": [
          "polly.amazonaws.com"
        ]
      }
    }
  ]
}