If Power Premium capacity has been purchased, the Power BI Report Server product key can be retrieved from the Power BI admin portal. The Power BI admin portal can be accessed by either an Office 365 global administrator or a user assigned to the Power BI service administrator role. For these users, a link to the Admin portal will be exposed from the gear icon in the top-right corner of the Power BI service:

The Power BI service administrator role and the assignment of this role in Office 365 were introduced in the Power BI Project roles section of Chapter 1, Planning Power BI Projects. Additionally, Chapter 12, Administering Power BI for an Organization, provides granular details on the Tenant settings available in the Power BI Admin portal and other topics related to governing Power BI deployments.

In the following screenshot, a Power BI service administrator has accessed the Capacity settings menu of the Admin portal:

Clicking the Power BI Report Server key icon on the far right of the Capacity settings menu launches a dialog containing the key. This 25-character key value can be copied and used to complete the installation of the server:

If Power BI Report Server is being licensed via SQL Server Enterprise Edition with Software Assurance, the product key can be downloaded from the Microsoft Volume Licensing Service Center (VLSC) via the following link: http://bit.ly/2rqefW1.

An instance of the SQL Server Database Engine is not required to complete the standalone installation of the Power BI Report Server. However, as discussed in the Hardware and software requirements section, a SQL Server database engine instance is required to configure the report server. The report server is not available until it's been configured, as described in the Configuration section.