choropleth plotly map displaying a white background

Question

I am trying to create a choropleth map of the uk using plotly, but every time I try, it outputs an empty page, or the json doesn't match with the dataframe.this is where i obtained the url for the dataframe Here's my code so far:

import pandas as pd
from urllib.request import urlopen
import json
with urlopen('https://raw.githubusercontent.com/deldersveld/topojson/master/countries/united-kingdom/uk-counties.json') as response:
    geojson = json.load(response)

url3 = 'https://api.coronavirus.data.gov.uk/v2/data?areaType=utla&metric=cumCasesBySpecimenDate&metric=cumPeopleVaccinatedFirstDoseByVaccinationDate&metric=cumPeopleVaccinatedSecondDoseByVaccinationDate&metric=newCasesBySpecimenDate&metric=cumPeopleVaccinatedThirdInjectionByVaccinationDate&format=csv'

df = pd.read_csv(url3)
df_new=df.replace("areaName", "NAME_2")


from plotly import graph_objects as go

fig = go.Figure(
    go.Choroplethmapbox(
                geojson=geojson,
                featureidkey="properties.NAME_2",
                locations=df["areaCode"],
                z=df['cumCasesBySpecimenDate'],
                zauto=True,
                colorscale='Reds',
                showscale=True,
         
    )
)

fig.show()