The last step is to select the layouts in “Layout” section of the new tab settings dashboard.
After selecting the typology, you can choose to show a singular content for the tab on all products, or to customize it right inside its configuration page. For the first case you will need to enable “Use the content for all products” field and insert the content in the specific section in the page.
On the contrary, tab is enabled on all related products (depending on selected tab typology), but it will be shown only after setting its content in product configuration page.
For all available details about layouts, please visit this page.