Read the article. He old-school snail-mailed it -- that is still a valid way to file.
Butner is whack, so it's easy to see how it got out of the prison.
But the dumbass clerk who filed it without reading it (...a Freeper?) should be fired out of a cannon.
…. except that it isn’t. That’s the whole point of the ECF system, to prevent any filings except those done electronically. The only time a paper copy of anything is accepted by the clerk through the mail is when a pro se party files it, and then the clerk has to manually scan and docket it electronically. However, the parties to this case, Trump and the government, are both represented by counsel. I suppose the clerk here would have scanned and docketed a candy wrapper if it had the right case number on it.