You cannot access the API Publisher Web interface using HTTP. It is exposed as HTTPS only.
The API Publisher log-in page opens as follows:
You can log in, you need to create a user and assign it specific permissions as described in section User Management. Alternatively, you can also log in to the API publisher as an administrator, by using the admin user that is available by default with the password also as admin. The default admin user has administrator privileges and can perform any operation.