A) you didn't actually say what your issue is? The photo doesn't show an "issue" with private networking.
B) assuming it is related to access through public network, it looks like you have reached the limit of your current plan and will need to upgrade.

when i click the link it doesn't work when i try to use it

it says not found

because thats the internal network

you need to upgrade your plan to add a custom domain

thats open to the internet

Private networking is for services to communicate with each other, not for you to access your service

That's what public networking is for

https://docs.railway.com/reference/private-networking

!s