I am not familar with that template, It may be worth getting in touch with whoever created it to find out how it works with Railway. Looking at the link I can’t access the github repos they are using behind them so it could be a manual process or you just need to click deploy.
I am not familiar with Railway and we don’t directly support that platform so this falls under a bit of a grey area as one of the requirements of self hosting is you have the knowledge to manage the application on the platform you are using.
Having said that with anything else it is just a care of deploying more worker containers so I suspect the template ceator is correct and I see no reason to doubt them.