The Vault Service account can access all of Enterprise Vault Reporting's reports. Other accounts must belong to an administrator role that allows access to the reports that you require.
See Administrator roles that provide access to Enterprise Vault Reporting's reports.
You can access Enterprise Vault Reporting's reports in the following ways:
From the Microsoft SQL Server Reporting Services Report Manager Web application.
See Accessing Enterprise Vault Reporting's reports from SQL Server Reporting Services Report Manager.
From the Enterprise Vault Administration Console.
See Accessing Enterprise Vault Reporting's reports from the Administration Console.