Bigcommerce give error on installing newly created draft app

Question

I have created a new app in Bigcommerce and just return hello world from there. on Login to backend and go to my draft app where i click on install app it shows me error :

{"message":"Request returned error code: 400 and body: {\"error\":\"invalid_client\",\"error_description\":\"Unknown client ID {rbruk81rd5fq4dteoeahxl1yh7tm008}\"}"}

I have followed this video : https://www.youtube.com/watch?v=Do1vRfEdn70

All the steps are fine but at the end it show error.

On running npm run build it works fine.

Can any one find out how to resolve that issue.

Edits : .env file

# Get the Client ID and Secret from the Developer Portal
    # https://developer.bigcommerce.com/api-docs/apps/quick-start#register-a-draft-app

    CLIENT_ID={rbruk81rd5fq4dteoeahxl1yh7tm008}
    CLIENT_SECRET={8d450e3542018e9f11a30bfdc5c2d09eb6cf06587fc38ee47a184f24b580fb55}

    # Test locally with ngrok
    # https://developer.bigcommerce.com/api-docs/apps/guide/development#testing-locally-with-ngrok

    AUTH_CALLBACK=https://c9e8-203-122-42-46.ngrok.io/api/auth


    # Specify the type of database
    DB_TYPE=MySQL

    # If using mysql, enter your config here
    MYSQL_HOST={localhost}
    MYSQL_DATABASE={ecommerce}
    MYSQL_USERNAME={root}
    MYSQL_PASSWORD={hestabit}