PINE64

I've installed ubbuntu  on my board and ran the resize_rootfs.sh script.  I tried to install MATE with:
sudo /usr/local/sbin/install_mate_desktop.sh

I get two errors"
E: Could not get lock /vat/lib/apt/lists/lock - open (11: Resource temporarily unavailable)
E: Unable to lock directory /var/lib/apt/lists

Did I miss a step?

that usually happens to me if another application has control of the apt lock. like if synaptic or aptitude is also currently running. or maybe also two instances of the script.