We're in the process of updating the admin experience. In the meantime, you may not need to click Directory to get to Managed accounts.
To view all the managed accounts for your organization at admin.atlassian.com, select Directory and then Managed accounts from the left navigation. You can also use the user management REST API to edit account details and change user account statuses.
From the Managed accounts page, you can search accounts by name and email address. When you enter search criteria that is more than 3 characters, we return results that match at least 3 continuous characters in your search criteria in addition to results that include the full string.