Fatal error … I cannot activate BuddyPress Courseware !!!

When I try to activate it, I get the following fatal error.

Fatal error: Cannot redeclare class FormBuilder in /index/wp-content/plugins/buddypress-courseware/assignments/formbuilder.class.php on line 6

What can I do?

https://ww.wp.xz.cn/plugins/buddypress-courseware/