Hello, can someone please tell me if there is an official way on how to install Mega SYNC on Solus?

No, apparently it can not legally be packaged.

Other than in respect of those parts of the code that were developed by other parties and as specified strictly in accordance with the open source and other licences under which those parts of the code have been made available, as set out on our website or in those items of code, 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.

Someone did ask this question before, the solution however depends on how much you trust a random person on the internet: https://discuss.getsol.us/d/903-install-mega-cloud/3

2 years later

@cipricus People already know about the flatpak. Please don't necro old topics.