It sounds like she has broken the law before, and is compounding that with even more of the same – secretly recording a meeting in a SCIF (Sensitive Compartmented Information Facility, or a secure room).
Here is the audio released by NBC News.
Her firing took place at the end of 2017. Effective in January of 2018, the White House banned the use of personal cell phones or recording devices while at work. As Sarah Sanders stated at the time:
The security and integrity of the technology systems at the White House is a top priority for the Trump administration and therefore starting next week the use of all personal devices for both guests and staff will no longer be allowed in the West Wing. Staff will be able to conduct business on their government-issued devices and continue working hard on behalf of the American people.