Finally, I resolved.
Copied files from update folder and replaced admin-panel folder.
Thanks for your support guys.
Yip I did the same thing.
For everybody else having problems with the install here are my steps.
I downloaded version 3.0.4 and went through the normal install procedure.
Then I uploaded the update.php file to root folder
This is where you should take note
There are 2 script folders. The script folder that is in the Update Guide folder is the one you need to upload and replace all files and folders.
Then in our browser point to https://<your domain>/update.php
You will then have to put in purchase code in which is
babiato-chintan-bhatt (you will find this at the bottom of the page.)
Took about 1 minute for the system to update.
Now I just need to test
Hope it helps someone out