When I try to activate the plug it will not activate and instead I get an error message

Fatal error: Cannot redeclare ss_url_key() (previously declared in /home2/txkingst/public_html/wp-content/themes/symbiostock/functions.php:54) in /home2/txkingst/public_html/wp-content/plugins/ss-network-graph/ss-network-graph.php on line 28

How was it resolved? Just curious.

updated version of software