Howdy,
How to actually display a widget in a CMS page
Edit the CMS template file
Find the CMS page template file:
Usually located at /themes/your-theme/templates/cms/page.tpl.
Insert your widget code ({widget name="store"}) directly in the template where you want it to appear.
{widget name="store"}
Tip: Always make a backup before editing any templates!
Clear your PrestaShop cache after making changes (Back Office: Advanced Parameters > Performance > Clear Cache).
Hope this helps