First of all, they were not looking for any specific documents. Look at Attachment B in the search warrant in the link below which shows property to be seized. They were searching for all documents with classified markings and presidential documents.
The search was recorded by FBI and also recorded by the Mar A Lago security system on media which was subpoenaed. Essentially everything the FBI did is recorded.
A federal judge unsealed the warrant and property receipt materials after the Justice Department requested their release.
www.npr.org