For AutocompleteWidget to be enabled in the admin, you should create your own admin/base_site.html template as demonstrated in test_project/templates/admin/base_site.html:
{% extends "admin/base.html" %}
{% load i18n %}
{% block footer %}
{{ block.super }}
<script src="{{ STATIC_URL }}jquery.js" type="text/javascript"></script>
{% include 'autocomplete_light/static.html' %}
{% comment %}
Load additionnal script or style dependencies here. For instance, the
double country/city autocomplete widget requires the countrycity deck
bootstrap so we'll load it. But you don't need this one if you don't use
the countrycity widget of the cities_light app.
{% endcomment %}
<script src="{{ STATIC_URL }}cities_light/autocomplete_light.js" type="text/javascript"></script>
{% endblock %}