Reporting Services service application need to be running in one of the application servers, then only reporting service feature could be used in SharePoint Integrated Mode.
The Reporting Services service application must be running in one of the application servers, then only the reporting service feature can be used in SharePoint Integrated Mode. The following steps must be executed to successfully create and configure the Reporting Services service application.Verify the Reporting Services SharePoint service is installed and started
Once the verification is completed and ensured that the SQL Server Reporting Services Service is running then we can create the service application.Create Reporting Services Service Application
Now the service application is ready to use in the SharePoint Farm.
SharePoint Online And Office 365 Administration