Are you trying to install SQL Server Reporting Services onto an already built default or named instance of SQL? Does it error out telling you that the instance already exists and you need to choose another, and you don’t wanna choose another?
Then you might want to read this. Yes, it is for a really old version of SQL, but hey, it works. I just tested this on SQL 2014.
Run the below command at the Windows command prompt to start SQL Server setup on the active node. Make sure to run this command after changing the root directory of the command prompt to the location where you have placed the SQL Server setup files.
Setup.exe /SkipRules=StandaloneInstall_HasClusteredOrPreparedInstanceCheck /Action=Install
This bypasses the SQL install logic checks. A downside is that the setup routine skips the auto-magic SSRS Native mode configuration. You will need to do a manual configuration of the SSRS using the Reporting Services Configuration Manager.
This is no way implies that if you do a SQL Availability Group, and put SSRS on both (or all) nodes, that the SSRS is now in a DR state. In fact, some really useful reading for doing the DR process with SSRS in this posture can be found here: