I'm not sure why they are suggesting to build it from scratch. Their source code license doesn't permit it.
This licence grants you the rights, and only the rights, set out below, to access and review Mega's code.
Additionally:
you are not entitled to use or do anything with the code for any commercial or other purpose, other than review and commentary on it.
We cannot provide it and it is in violation of the license to do anything that would entail using their source code for anything besides reviewing (auditing) it, such as re-packaging or providing packaging instructions.
Integration of Mega into any of the file managers (we do not develop one, there is no "Solus file manager") would involve reviewing their code and violating their license in the process, since the purpose of reviewing the code would be beyond that very review or any "commentary" on it.
