After installing Directories from Product Updates, you will need to build a Lightning Component for your Directory. You will be unable to access the front end of your Directory until your Lightning Page has been created. This can be done by following the steps below:
Creating a Lightning Page:
From the top-right corner of your screen, click on the Setup hyperlink.
From the Setup page, type All Communities in the Quick Find/Search bar in the left-side panel.
From the left-side panel, underneath the Quick Find/Search Bar, click All Communities.
From the All Communities page, click the Community Workspace of Community the you would like to add your Directory to.
From the Community Workplace page, click on the Builder panel.
From the Builder page, in the top left corner, click Home.
From the Home drop down menu, click + New Page.
From the New Page modal, select Standard Page.
From the New Page modal, select 1 Full-Width Column and click the Next button.
From the New Page modal, in the Name field typeType] SearchDirectory, and click the Create button. The name must be "SearchDirectory" with no spaces. If you use "Search Directory," this will fail.
From the Builder page, in the top-left corner, click on the Lightning Bolt icon (Components) button.
From the Components drop down menu, search for SearchDirectories.
From the Component drop down menu, drag and drop the SearchDirectories component into the Content space/section. After dragging and dropping the component, you should see the Directory Not Found message (see screenshot) appear in the Content section.
From the top right corner of the Builder, click on the Publish button.
From the Builder page, in the top-left panel menu, click on the Gear icon (Settings) button.
You have now successfully created your Lightning Page and can return to your Salesforce org.