Trouble setting up Sanity with Next.js app

Hello, been trying to setup Sanity with a nextjs app but having 0 luck. I am basically doing

npx create-next-app

with it's default structure. Here I can connect just fine to my Sanity dataset (through these steps: https://www.sanity.io/docs/connect-your-content-to-next-js ). Now I want to have Studio running seperately, so I run

pnpm create sanity@latest

and run through the questions (I basically want it to run studio alongside my dev build, not embedded, so I say no to adding the config in nextjs) but everything I try always ends up in error, I'm currently plagued by: when going to localhost:3333.

Can you share your code?