hi,
i had the same problem. the plugin root doesn’t work, you need to change the constant.
find :
// define(PLUGIN_ROOT, substr(str_replace("\\", "/", dirname(__FILE__)), 0, strpos(str_replace("\\", "/", dirname(__FILE__)), "/".PLUGIN_NAME))."/".PLUGIN_NAME);
replace by :
define(PLUGIN_ROOT, DOCUMENT_ROOT."/wp-content/plugins/insert-link-class");
it worked for me.