If you are not the intended recipient, please notify the sender at the above contact information immediately and destroy all copies of this message and any attachments. Please find attached the following required documents: • Application...
Shin Chan is correct, the third choice requires a definite article. "Please find" is a business-jargon cliche. If the documents are not literally "attached" by staples or paper clip (or even if they are), you may substitute
Or, I would write "I have enclosed/attached the following documents:" with a list.
"Please find attached" is letting the reader know that something is attached in the email. And yes, this can be necessary, as some people really do miss that little paperclip icon denoting an attachment.
Both ways are correct, but you need say "documents". "All" implies there is more than 1 document. If there's only one document, then the sentence would be "Please find attached the required document (the document required)".