SolidOS cloned repo not serving, although server running

I cloned the SolidOS repo as described in the README of GitHub - solid/solidos. an npm start tells me the server is running on localhost:8443. when accessing that with my browser, I get ERR_empty_response.
I’ ll attach the console output:

lerna notice cli v3.22.1
lerna info versioning independent
lerna info Bootstrapping 5 packages
lerna info Symlinking packages and binaries
lerna success Bootstrapped 5 packages
  solid:settings Server URI: https://localhost:8443 +0ms
  solid:settings Auth method: oidc +4ms
  solid:settings Strict origins: true +0ms
  solid:settings Allowed origins:  +0ms
  solid:settings Db path: ./.db +0ms
  solid:settings Config path: ./config +1ms
  solid:settings Suffix Acl: undefined +0ms
  solid:settings Suffix Meta: undefined +0ms
  solid:settings Allow WebID authentication: true +0ms
  solid:settings Live-updates: true +0ms
  solid:settings Multi-user: true +0ms
  solid:settings Suppress default data browser app: undefined +1ms
  solid:settings Default data browser app file path: default +0ms
  solid:settings CORS proxy listening at /proxy?uri={uri} +21ms
  solid:settings Base URL (--mount): / +20ms
  solid:settings SSL Private Key path: ../privkey.pem +0ms
  solid:settings SSL Certificate path: ../fullchain.pem +1ms
Solid server (v5.6.4-3-g1afe2f45) running on https://localhost:8443/
Press <ctrl>+c to stop
  solid:authentication Provider keys loaded from config +0ms
  solid:authentication Provider keychain initialized +72ms
  solid:authentication Not sleeping before client registration... +2ms
  solid:authentication Client not present for issuer https://localhost:8443, initializing new client +3ms
  solid:authentication Registering new client for issuer  https://localhost:8443 +1ms
  solid:authentication Local RP client initialized +306ms

additional info about the proceeded steps can be found at Documentation SolidOS setup - HackMD

any ideas ?

solved Documentation SolidOS setup - HackMD