That build command will run a server, which our hosting does not permit. It looks like this is “intended to be” a dynamic project - from a directory called “backend” - so maybe not suitable for our hosting.
Check out our hosting philosophy here:
If you can instead build your site into some static html/css/js without leaving a server running, so we can serve just those static files, then you’ll probably have a different command - something like “npm run build” and maybe the copies but not “running” a server - then we should be able to host that part of your site!