I would like to install Confluence on the same machine with jira software and database postgresql

[Sebastian_Kalata]

Current situation: I have Jira Software and Jira Service Desk installed on a server with postgresql database.

I would like to install Confluence on the same machine so that everything works properly. How do I do this or where can I find step by step instructions?

[Dave Theodore _Coyote Creek Consulting_]

It's no different to setting it up on a separate machine.  You create an environment for it to run in, create a database instance, then point to that database.  I would recommend running the Confluence process as a different user and using a different database user to segregate the two applications, though.