To create a super user: $ python manage.py createsuperuser

from django.contrib import admin
from catalog.models import Author, Genre, Book, BookInstance

admin.site.register(Book)
admin.site.register(Author)
admin.site.register(Genre)
admin.site.register(BookInstance)

También puedes hacerlo con clases:

class CoopolisAdmin(AdminSite):
    site_header = "Coópolis Backoffice"
    site_title = "Coópolis backoffice"
    index_title = "Benvingut!"


coopolis_admin_site = CoopolisAdmin(name='coopolis_admin')
coopolis_admin_site.register(User)
coopolis_admin_site.register(Project)
coopolis_admin_site.register(Course)
coopolis_admin_site.register(Activity)

Las url estarían en coopolis_admin_site.urls:

urlpatterns = [
    path('entity-admin/', admin.site.urls),
    path('event-admin/', coopolis_admin_site.urls),
]

admin.site.site_header = "UMSRA Admin"
admin.site.site_title = "UMSRA Admin Portal"
admin.site.index_title = "Welcome to UMSRA Researcher Portal"

class Category(models.Model):
    ...

    class Meta:
        verbose_name_plural = "Categories"