The problem here, as I understand it, is the Mac OS Finder, which creates a .Trash folder on the removable media device (e.g., SD card), which will cause SD scripts like the activator script to fail. It's not that Mac OS corrupts these files during download or extraction -- assuming your Mac has a tool (command) to extract a multi-part RAR.
If you have the files downloaded from Mega already on your Mac desktop, why not use a Terminal window to copy these to removable media? I assume you downloaded a collection of RAR files from the Mega site. --g
If you have the files downloaded from Mega already on your Mac desktop, why not use a Terminal window to copy these to removable media? I assume you downloaded a collection of RAR files from the Mega site. --g