Error in activating the plugin

Hi team,
I am very happy to see a great plugin for maintaining courses. I was trying to install plugin as mentioned in installation guide. But I face issue while activating it.

Plugin could not be activated because it triggered a fatal error.

Fatal error: Can’t use method return value in write context in /home/kannatci/public_html/wp-content/plugins/lifterlms/includes/models/model.llms.course.php on line 424

Could you please help?

Thank you