Thanks for sharing the project details. I checked your build logs and the project. It seems like you are running node server.js, which is used to run Node.js on servers like EC2. Because Vercel is a serverless platform this command will not work and lead to failed builds.
I’d encourage you to read the Using Express.js with Vercel and update the application code to work with Vercel. These changes should be relatively smaller. You can also look at the Express example solution that works on Vercel.