Hi Jersey,
This plugin is responsible for adding new tabs.
The layout is defined by your theme and css styles.
The default layout of WooCommerce tabs is horizontal, but your theme or actual css settings change it to vertical.
You can use another theme that do leave the layout vertical, or ask your site designer to apply custom css to change your existing them’s layout of WooCommerce tabs.
I hope this information help you to achieve the appropriate layout.
Regards,
Peter