xubuntu – How to allow connection to google compute engine ubuntu VM external ip adress?

I’m attempting to setup a web app on a google VM (Heres the docs to what im trying to set up: https://cms.readthedocs.io/en/v1.4/index.html)

I’m really new to backend & linux as a whole so sorry in advance if i say something stupid 🙂

It seems to have installed correctly but when I try to start a process I get this error: “Service serviceThatITriedToStart could not listen on specified address, because it is not available.”

I have reserved a static external ip on google cloud and added it to the config file so a service setup looks like this:

    "LogService":        (("externalIP", 29000)),

Previously where I put externalIP there was localhost.

I had set up this on a local VM and everything worked while using localhost –
As far as I have gathered it is either google cloud’s firewall that is blocking me or something within ubuntu. (On the VM instance I have enabled to allow http & https traffic)

As I said I’m very new to this and hopefully my question makes any sense.
Thanks in advance