Resource handler returned message: "<resourceName> already exists

Hello.

An S3 bucket cannot be created unless it has a public and unique bucket name.
Therefore, if a user with another AWS account is creating an S3 bucket with the same name, you will not be able to create it.
Try creating it with a different S3 bucket name.
https://repost.aws/knowledge-center/s3-error-bucket-already-exists

These error messages indicate that another AWS account owns a bucket with the same name. If you get any of these errors, then you must use a different bucket name to create the bucket.

If you get the Bucket name is already owned by you or BucketAlreadyOwnedByYou error, then check your account for a bucket with the same name. These errors indicate that your account already uses the bucket name. You can use the Amazon S3 console to review existing buckets. Or, you can run the head-bucket AWS CLI command to confirm that you already have a bucket with that name.

Moreover, you may need to either randomise bucket name creation:

BucketWithSemiRandomName:
  Type: "AWS::S3::Bucket"
  Properties:
    BucketName: !Join
      - "-"
      - - "bucket-with-semi-random-name"
        - !Select
          - 0
          - !Split
            - "-"
            - !Select
              - 2
              - !Split
                - "/"
                - !Ref "AWS::StackId"

Or just hardcode/parametrize the bucket name with a global name, so that next time you run the IaC it won’t try to recreate it. You can do this by setting the retain property and use the import command: https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/resource-import-existing-stack.html