The US government can run warrantless wiretaps by sending Section 702 data requests to communications providers (iCloud, Gmail, FB Messenger, Skype, etc.) on people who aren't US citizens who live outside the US if they are suspected to be relevant to national security (email communications, chat communications, etc.). US law allows the FBI to search these foreigner's communications for mentions of Americans who are suspected to pose a national security risk without a warrant. Any other searches of this data related to Americans requires a court order.
Here is a better article by a reporter who understands what the government's report said: https://archive.is/jgWUt
Jeez reading over some of the other literature I could find looks like they can issue “batch jobs” to run many queries without having to do them manually/wait. Makes me think performance isn’t that quick and that there is an ungodly amount of data they are querying.