You can also use plowshare https://github.com/mcrapet/plowshare. But it's also a command line tool.
My suggestion: learn to use the command line. It's quite useful for many small (and complex) tasks.
You can use Plowshare for this: https://github.com/mcrapet/plowshare
It has a module for Mega: https://github.com/mcrapet/plowshare-module-mega
Plowshare is small command line tool. It's written in bash and you don't need to install additional packages. It works very well.
Here is a small tutorial how to install it on a seedbox: https://whatbox.ca/wiki/plowshare
It should work on other seedboxes in the same way.
Are you comfortable with command line? If so try https://github.com/mcrapet/plowshare/. But it was last updated 2 years ago, so the mediafire plugin may not work. There are other ways to upload to mediafire but I don't think it's possible on USB.
use rar to split the files, plowshare to upload: https://github.com/mcrapet/plowshare
follow step 2 installation of modules: https://github.com/mcrapet/plowshare/blob/master/INSTALL
edit zippyshare.sh and change this line: if [ "$SZ" -gt 209715200 ]; then
to
if [ "$SZ" -gt 524288000 ]; then
Plowshare supports a few of them but I generally just avoid them. It's been a long time since I've needed to download something from a site like that.
Reminds me of something I made long time back to get direct download links off mediafire. It was a huge hit in my college because they banned mediafire, and my site would still work (It was called mediafireroaster). It used a bit of code from plowshare for regex.
Stopped working after mediafire launched a new design, but it was good while it lasted.
Mediafire has a client for Linux that you can upload from. About the fileupload plugin, I don't think it still works with plowshare. You could try using plowshare directly.
I only know of uptobox as the only one that supports FTP upload but they are not available in US (you could use a VPN to access them) and the upload speed is kinda slow.