Hello Pat.
The log you posted doesn't show the exact error, just that it happens when running the post-installation script. That script requires admin rights because it tries to create a file in /usr/share. The installer should have asked about your admin password before that - did it do it?
I'm going to try to install El Capitan to reproduce the problem, but I may fail or it will at least take some time. In the meantime you could try running just the post-install script to see if it will give any errors. I've attached the script, it's very simple. To test it, open a terminal window, change to the Downloads folder with
cd ~/Downloads
then start it with
sudo ./PostInstall.sh
and type your admin password. The script should just print Success if there are no errors, but hopefully there will be some :)
Ivan Kolev (Software Developer, EPHERE Inc.)
E-mail: ivan.kolev at ephere dot com
Discord: ikolev