Cannot activate plugin

Hello,
I get this error message when I try to activate the plugin.

Warning: require_once(__DIR__/composer/autoload_real.php) [function.require-once]: failed to open stream: No such file or directory in /home2/myworks1/public_html/wp-content/plugins/popup-scroll/vendor/autoload.php on line 5

Fatal error: require_once() [function.require]: Failed opening required '__DIR__/composer/autoload_real.php' (include_path='/home2/myworks1/public_html/wp-content/plugins/google-analytics-for-wordpress/vendor/yoast/api-libs/google:.:/usr/lib64/php:/usr/share/pear') in /home2/myworks1/public_html/wp-content/plugins/popup-scroll/vendor/autoload.php on line 5

How can this be fixed? What am I doing wrong?

https://ww.wp.xz.cn/plugins/popup-scroll/