Beatbox project help

Hi all,
I am currently attempting the beatbox challenge.

when i run npm start server it start it all right on port 4001… but when i go to all it returns is “Cannot GET /” I’ve tried it with chromium brower version:
Version 76.0.3809.100 (Official Build) Built on Ubuntu , running on LinuxMint 18.3 (64-bit)

also with firefox: 68.0.1

any help appreciated.