The portfolio is based on projects that are created from Dashboard -> Portfolio. The template you chose is meant to render those projects into this page. It doesn’t render the content you place in the Builder or the WP Editor.
To show the projects you go to Dashboard -> Portfolio -> Add new. Add all the projects you want with descriptions, etc. Then Create a page with template Portfolio selected, change its layout from the metabox and click save (No need to enter any content there). Finally click View Page, you should see all the projects you’ve created.
Let me know if you had any troubles.