Best bet for FREE is DaVinci Resolve. It is a powerful video editor.
https://www.blackmagicdesign.com/products/davinciresolve/
You can also purchase Final Cut Pro X or an Adobe Premiere subscription.
I can't speak for Flyboost specifically, but i use Jammtext and Instagram no longer works due to instagram stopping certain API's. I would think Flyboost suffered the same loss.