The Mate themes should be there in the official repository, separate from the Yaru themes, just install them with Synaptic or the command line. No need to unzip or move, they go right where they belong.
sudo apt-get install mate-themes
mate-themes
Official themes for the MATE desktop
This package contains the official desktop themes of the MATE desktop
environment.
The themes provided for the MATE desktop partially resemble themes that
are well known from GNOMEv2 desktops. However, the MATE team also prepared
some new themes esp. for MATE (Menta, GreenLaguna, TraditionalGreen,
TraditionalOk, and BlackMate).