1. Using Paloalto firewall in-house.
2. Permits S3 bucket via Paloalto URL filtering in-house.
3. The access URL for the AWS S3 bucket can be found at https://docs.aws.amazon.com/general/latest/gr/rande.html.
4. I want to know the URL that should be allowed when using CloudBerry Explorer pro program.
Sorry, not sure what you mean by "URL that should be allowed when using CloudBerry Explorer", but if you're referring to WEB URLS for the files they would have this format:
http://bucketname.s3.amazonaws.com/pathtothefile/file.txt