In most cases, adding any service, such as SSAS, SSRS, or a database engine, to an existing installation is not possible, and such additions require a named Instance installation.
This problem first appeared in 2013 on a SQL server 2008 R2 that was running on Windows Server 2008 R2.
However, this was not a typical situation, and the client requested that we add SSRS to an existing SQL Server installation. This is when things started to get interesting, because the SQL installation wizard would fail during the installation rules check. see the illustration
SQL Server is already installed and clustered on the server, according to the error.
To fix this error, start an elevated command prompt window and navigate to the location where your setup files are located. now Run SQL Server setup.exe with the values listed below.
Setup.exe /SkipRules=StandaloneInstall_HasClusteredOrPreparedInstanceCheck /Action=Install
When you press enter, you’ll be sent to the initial setup page, where you’ll see the screenshot below.
Setup will skip that check, and you’re fine to go with the installation.
The identical procedure should be followed on the passive node so that both clustered nodes have the same binaries.