django tinymce struggles

# admin.py
from django.contrib import admin
from tinymce.widgets import TinyMCE
from django.db import models
from .models import User, Announcement

class AnnouncementAdmin(admin.ModelAdmin):
    fields = ["title",
              "content",
              "author",
              "published"
            ]

    formfield_overrides = {
            models.TextField: {'widget': TinyMCE()}
        }

admin.site.register(User)
admin.site.register(Announcement, AnnouncementAdmin)

# models.py
from django.db import models
from django.utils import timezone

class User(models.Model):
    username = models.CharField(max_length=30)

    def __str__(self):
        return self.username

class Announcement(models.Model):
    title = models.CharField(max_length=50)
    content = models.TextField()
    author = models.CharField(max_length=30)
    published = models.DateTimeField('date published', default=timezone.now)

    def __str__(self):
        return self.title

# settings.py
INSTALLED_APPS = [
    ...
    'tinymce',
    ...
]
...
# tinymce settings
TINYMCE_DEFAULT_CONFIG = {
    'height': 360,
    'width': 1120,
    'cleanup_on_startup': True,
    'custom_undo_redo_levels': 20,
    'selector': 'textarea',
    'theme': 'modern',
    'plugins': '''
            textcolor save link image media preview codesample contextmenu
            table code lists fullscreen  insertdatetime  nonbreaking
            contextmenu directionality searchreplace wordcount visualblocks
            visualchars code fullscreen autolink lists  charmap print  hr
            anchor pagebreak
            ''',
    'toolbar1': '''
            fullscreen preview bold italic underline | fontselect,
            fontsizeselect  | forecolor backcolor | alignleft alignright |
            aligncenter alignjustify | indent outdent | bullist numlist table |
            | link image media | codesample |
            ''',
    'toolbar2': '''
            visualblocks visualchars |
            charmap hr pagebreak nonbreaking anchor |  code |
            ''',
    'contextmenu': 'formats | link image',
    'menubar': True,
    'statusbar': True,
    }

# urls.py
from django.contrib import admin
from django.urls import path, include
from . import views

urlpatterns = [
    ...
    path(r'^tinymce/', include('tinymce.urls')),
]