How to enable from Plex port forwarding successful setup for Plex to work on Sonos

I have downloaded Plex on my laptop (MacBook) and all works extremely well for playing my library of tunes but I wish to play this library via Sonos which is the main way I listen to music in mu home

I am reluctant to purchase Plex Pass for mobile access until I’ve got Plex working on my home system first …I have has Sonos technical support who confirm I have loaded Plex properly i.e. server connection etc , however they inform me tat “port forwarding” from Plex to enable using Plex on my Sonos system is outside their control

I am sure this is not the first occasion that this has happened , so if someone can assist me with a simple step by step guide or provide a reference to overcome this issue I would be very grateful

many thanks

Tony Dunne Liverpool