No module error while trying "Connect to AWS IoT"

I have followed the "Connect to AWS IoT" steps provided in AWS IOT (1.Register a device 2.Download a connection kit 3.Configure and test your device). When I tried to run the script, I am getting No module named AWSIoTPythonSDK.MQTTLib

Environment: Platform: Linux Choose a AWS IoT Device SDK: Python

More info:

user::~/Downloads/connect_device_package$ ./start.sh 

Downloading AWS IoT Root CA certificate from AWS...
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100  1188  100  1188    0     0   7378      0 --:--:-- --:--:-- --:--:--  7378

Cloning the AWS SDK...
Cloning into 'aws-iot-device-sdk-python'...
remote: Enumerating objects: 870, done.
remote: Counting objects: 100% (135/135), done.
remote: Compressing objects: 100% (77/77), done.
remote: Total 870 (delta 71), reused 58 (delta 58), pack-reused 735
Receiving objects: 100% (870/870), 334.31 KiB | 1.92 MiB/s, done.
Resolving deltas: 100% (423/423), done.

Installing AWS SDK...
~/Downloads/connect_device_package/aws-iot-device-sdk-python ~/Downloads/connect_device_package
Requirement already satisfied: AWSIoTPythonSDK in /home/om/.local/lib/python3.8/site-packages (1.4.9)
~/Downloads/connect_device_package

Running pub/sub sample application...
Traceback (most recent call last):
  File "aws-iot-device-sdk-python/samples/basicPubSub/basicPubSub.py", line 18, in <module>
    from AWSIoTPythonSDK.MQTTLib import AWSIoTMQTTClient
ImportError: No module named AWSIoTPythonSDK.MQTTLib