adding s3 website endpoint as alias

It is hard to tell since some of the key information is obfuscated, but I would say you can start by checking the name of the bucket in S3 matches the hostname in Route 53. If your site name is "my.example.com" then S3 required that the content be stored in a bucket called "my.example.com". It cannot be a bucket called "my" or "example.com" or any other name. It has to exactly match the hostname, and it must be lower case.

Also to support requests from both the root domain and subdomain, you must create two buckets. For example "my.example.com" and "www.my.example.com". You can view instructions on how to setup here.