These tapes have been on NABULeaks on Youtube for months.
https://www.youtube.com/channel/UCy5CvZAyn7skY1OCrg0VcYw
Looks like this is a new set though, released just 5 hours ago.
The purpose of the Logan Act is to punish political speech that runs counter to the sitting presidents foreign policy goals. Every previous invocation of the law has been to threaten somebody from an opposing political party for getting involved in foreign policy in a way that displeases whoever has control of the White House.
One call from Biden is Feb 27 2017, with security staff introducing him.
He’s a private citizen then.