How can I use a second nginx web app (swizzin) alongside virtualmin nginx site?

I have a goal of using my VPS for web host and seedbox. I cant figure out a way to get it to work with it. Currently every subdomain (including the one I configured swizzin to use) goes straight to the Virtualmin "under construction" page. Could anyone help me out (with detailed instructions because i'm very bad at this). I have tried some suggestions of reverse proxy and upstream but was unable to get it to work. Currently at 4 days of trying to do this.