MYSQL data in WP List table

Hello,

I’m busy to write my own plugin for WordPress (It’s for my own). I have now that the data from an mysql table shows on the plugin page. I used an Bootstrap table. Now I want to show the data in an WordPress table. An WP List Table. In the WordPress docs I cannot find an solution to use the WordPress table with data from another MYSQL table. I have used this tutorial: https://www.sitepoint.com/using-wp_list_table-to-create-wordpress-admin-tables/ but the table don’t show. Can anybody help me?

Thank you!