authenticate with express, passport, jwt, etc

I followed this tutorial step by step: https://www.digitalocean.com/community/tutorials/api-authentication-with-json-web-tokensjwt-and-passport

When I was done, I used postman. ipaddress/signup with the appropriate body variables

I get a 404 error. I did some other parts. I can see that the app.use(/, routes) method works. I put a hello world block in the routes.js to see if it was being reached. It worked.

router.get(‘/’, function (req, res) { res.send(‘hello world’) });

I’m new to node.js, so I am open to user error, but I have been doing web development for some time. I have even used nodejs in other contexts. This has got to be my fourth or fifth attempt to figure out this express, router, JWT thing. I need to be able to authenticate, so I have to figure this out. I figured using digital ocean’s tutorial was a good start. Every other tutorial I have used works. But those are admin tasks.