Hi there, welcome to the community!
From the looks of things, the themes are installed, but some of them are not quite compatible with MATE. That particular article doesn't address any MATE compatibility: 
How to Install Numix
Works on GNOME, Unity, Xfce and Openbox.
For Numix in particular, you can install the Numix GTK theme following these commands.
sudo add-apt-repository ppa:numix/ppa
sudo apt-get update
sudo apt-get install numix-gtk-theme
Some elements of the incompatible themes should work, like the icons - but may not behave properly then the designers intended (like the material design inspired one -- Adapta)
You can of course mix-and-mash and manually specify the controls, window border, colour and icons that would be used by that theme.
Another member has a link for 9 MATE compatible themes:
Take a look at the themes tag too for other compatible candidates if you're looking for themes. 