The feature to add a custom tab with content is not yet available with the free version of WP Travel Plugin.
However, it is a requested feature and has been scheduled to be added to our premium WP Travel Utilities addon. The feature will be available with the update to our utilities addon.
As for now, if you wish to get the feature for your website through customization, you can choose to hire a customizer to customize the plugin with this feature ( and any other feature of your choice ).
To hire a customizer for the task, please go through the link here :