Hi,
In order to get help, you should indicate the steps you followed to have this result.
Trying to guess, the backend part didn't started correctly.
I'd suggest to run in 2 separated consoles, so you can see the log of backend (be) and frontend (fe) separated
npm run be:start
npm run fe:start
These 2 commands will start the backend on port 8080 and the fe on port 8081 (proxying the backend).