In regards to the Windows Port instructions, it's been pointed out to me that the step involving transfer-to-s3 is no longer exists in the same way. I went into a recent build (15606) and I see now that the step is called upload-file-to-s3 and it doesn't contain an S3 URL. I have gone back and found that Build 15405 was the last one to use transfer-to-s3. Discussed in https://github.com/WebKit/Documentation/issues/85.
<rdar://problem/125566369>
As Brianna mentioned on GitHub: The link to download the archive is now in the compile-webkit step so you no longer need to look in the logs for a URL. Hope that helps! Closing.