I moved your topic to AUR - this is a custom package - I suggest you rebuild it - as custom packages may cease functioning without warning.
Please see → [Need-To-Know] About Manjaro and AUR
sudo pacman-mirrors -aS unstable
sudo pacman -Syu base-devel
git clone https://aur.archlinux.org/megasync.git
cd megasync
makepkg -is