Fatal Error upon plugin activation

I am installing this plugin on a staging version of my website in order to tie in the Eventbrite API plugin. Upon activation I received the following message:

Fatal error: Cannot redeclare class Keyring_Error in /home/ctadmin/public_html/drumstickdash/wp-content/plugins/keyring/keyring.php on line 309

Any ideas on what I can do to resolve this issue?

Thanks!

https://ww.wp.xz.cn/plugins/keyring/