That's not how it works. All Epstein has to do is give up names and dates, etc. Its up to the Feds to investigate and find the evidence regarding the info that was told to them. Once the feds investigate the info they were given if that is deemed good and credible info. That is when they will sign off that deal Epstein lawyer is trying to get.
The deal is drawn up but its only signed off by the feds if the info is credible and leads to them being able to prosecute the people Epstein telling on. After that its still up to a judge if he wants to honor that agreement between Epstein and the gov't.