It’s a lot simpler than you think…… If you installed picoreplayer and you’ve got a spare SD card I’d give it a go - you’ll be fine. It’s a 5 min job honestly…. And (assuming a standalone Pi) you don’t need to deal with any of these: installing dependencies, checking privileges, path locations and auto-boot options.
Follow this Setting up a Raspberry Pi2 with RoonBridge Step-by-Step (OSX version) or if you’re on Windows, replace Terminal with the Putty program, ApplePiBaker with whatever you used to write your picore SD card.