Log in to the AWS Console and navigate to S3.

Create an S3 bucket (define the Bucket Name and the Region).

Upload content to your S3 bucket.

Go to Properties > Static website hosting, choose Edit. Set Static website hosting to enabled and define the Index Document (does not need to exist, e.g. index.html).

Under Permissions, edit Block public access (bucket settings) and clear Block all public access, and choose Save changes.

Use the following example to add a Bucket Policy (replace example-bucket with your S3 bucket name).

{
    "Version":"2012-10-17",
    "Statement":[{
        "Sid":"PublicReadGetObject",
        "Effect":"Allow",
        "Principal": "*",
        "Action":["s3:GetObject"],
        "Resource":["arn:aws:s3:::example-bucket/*"]
    }]
}

Test the accessibility of your S3 bucket with the Endpoint URL.

curl -I http://keycdn-bucket.s3-website.eu-central-1.amazonaws.com/keycdn-logo.png
HTTP/1.1 200 OK
x-amz-id-2: IqlLQd9fwZglV4qlKHDHQsevt9l4V/8tczzRV29O0cc9uEYkAivXnaAjriCIu5bxK6Fr+vPW3JI=
x-amz-request-id: 98X9QN2N3HATC80S
Date: Tue, 09 Nov 2021 13:04:53 GMT
Last-Modified: Tue, 09 Nov 2021 13:03:33 GMT
ETag: "ea008842926a0d2f69dec3fd7462fde8"
Content-Type: image/png
Server: AmazonS3
Content-Length: 6050

Log in to the KeyCDN dashboard and create a Pull Zone using the S3 Endpoint as your Origin URL (e.g. http://keycdn-bucket.s3-website.eu-central-1.amazonaws.com).

Access your content through the Zone URL (e.g. https://example-hexid.kxcdn.com/keycdn-logo.png).