Hello,
According to a Clipchamp Support article, "Stock media files may not be redistributed, used in other editing programs, shared, or sold." Therefore, it appears that you cannot extract the audio file and use it in other software or services, or sell it as material.
If you export a video containing stock files and have paid for one of their subscription plans, you have the right to use the video for both commercial and non-commercial purposes, and to share it freely on social media and other platforms. You may want to consider editing it in a way that does not violate copyright.
For more information on this, please see the support article below.
Why does my Clipchamp video get a copyright warning on YouTube or other sites?
To be sure, it is best to consult a legal professional.