Ok, now it prompts it, so yes, it was the right url.

  │ Choose software to install:                                             │
  │                                                                         │
  │                 [ ] Basic Ubuntu server                                 │
  │                 [ ] OpenSSH server                                      │
  │                 [ ] DNS server                          ▒               │
  │                 [ ] LAMP server                         ▒               │
  │                 [ ] Mail server                         ▒               │
  │                 [ ] PostgreSQL database                 ▒               │
  │                 [ ] Print server                        ▒               │
  │                 [ ] Samba file server                   ▒               │
  │                 [ ] Tomcat Java server