This is correct. The name and password you created in the web interface is only valid in the web interface. The "octopi login" and password requested are a username and password for the underlying Linux operating system. By default, this is "pi" and "raspberry" (as you have tried). Make sure your caps-lock is not on; the password is case-sensitive. International keyboards may also make entering a password challenging if they are not yet configured.
OctoPrint is intended as a "headless" server, which you access from a different computer on the network. What you are trying to do is add a "local" screen. This can be done, but it requires some additional steps, including logging in to the underlying OS, installing some additional software and making some configurations there.