Before to set the “Portfolio page” you have to install the “Croccante PRO Portfolio” plugin. To to this just go to your WordPress Dashboard under “Appearance-> Install Plugins”. Install and activate the plugin (you can also install “Croccante PRO Shortcodes” if you want).
After activating the plugin, create a new page and choose the “Portfolio Main Page” template, save the page. Now this page will be the portfolio main page. If you want you can insert content into the page and will be shown above the portfolio.
To add new projects in the portfolio go to your WordPress Dashboard under “Croccante Portfolio-> Add New” and create your projects. Projects can be filtered by using categories. Subsequently, in “Appearance-> Customize-> Croccante PRO Theme Options-> Portfolio” you can set the number of project to show per page and the order.
If you notice that your portfolio pages aren’t working (404 error), go to your WordPress Dashboard under “Settings-> Permalinks” and save the page (no need to change anything, just save the page).
This should fix the problem.