Mysql problem

I have a problem on pschology tests plugin. it’s
Fatal error: Class ‘mysqli’ not found in /home/yenirehberlik/public_html/wp-content/plugins/wp-testing/vendor/ruckusing/ruckusing-migrations/lib/Ruckusing/Adapter/MySQL/Base.php on line 1259

http://www.yenirehberlik.com
https://ww.wp.xz.cn/plugins/wp-testing/