Can anyone assist with eliminating this error in order to install a new theme plugin?
Install plugins from the Moodle plugins directory
There is a request to install plugin Adaptable (theme_adaptable) version 2016102300 from the Moodle Plugins directory on this site. However, the location /var/www/html/moodle/theme is not writable. You need to give write access for the web server user to the location, then press the continue button to repeat the check.