Django Rest - TemplateDoesNotExist: How to solve it?

Before anyone asks, I've checked a lot of answers, and 'rest_framework' is listed on my Installed Apps. I have created a new venv and installed all dependencies on it again and still the same error.
When I try the url http://127.0.0.1:8000/admin I get the error template TemplateDoesNotExist at /Admin. When I try any endpoint of my API I get the same error.

I'm a bit confused because this project was running on my computer 1 month ago, but I got a problem in my computer and had to format. When I cloned the project again, got this error.

I'm going to list some of my settings about directory folder, I'm having a bad feeling about it.

TEMPLATES = [
    {
        'BACKEND': 'django.template.backends.django.DjangoTemplates',
        'DIRS': [os.path.join(BASE_DIR, 'build')],
        'APP_DIRS': True,
        'OPTIONS': {
            'context_processors': [
                'django.template.context_processors.debug',
                'django.template.context_processors.request',
                'django.contrib.auth.context_processors.auth',
                'django.contrib.messages.context_processors.messages',
            ],
        },
    },
]

STATIC_URL = '/static/'

STATIC_ROOT = os.path.join(BASE_DIR, 'static')

STATICFILES_DIRS = [
    os.path.join(BASE_DIR, 'build/static'),
]

Folders structure is:

Appapi/
   movies/
     settings.py
     urls.py
     wsgi.py
   imdb/
     migrations/
          migrationsfiles....
     models.py
     views.py
     serializers.py
     ...
   venv/
manage.py
README.md
requirements.txt

And some other files, like gitignore, procfile, etc.

Some of the errors traceback: django.template.exceptions.TemplateDoesNotExist: index.html

line 47, in select_template
raise TemplateDoesNotExist(', '.join(template_name_list), chain=chain)  

Edit:
Django version 2.1;
I don't have a templates directory, I'm using rest-framework to make an API, so I'm not dealing with html, css and js with Django.