After buying the system you must download and extract the main-file-zip.
Upload
Then open it, and upload the inventory main-file to public-html or make a subdomain and upload the system on it.

Extract main-file-zip
After uploading the inventory main-file on your server, extract and then open it.

Delete zip file
After making sure that the movement was complete, delete the inventory main-file and zip files.

Config
Put the site or Subdomain link on application/config/config.php. For doing this, from application part go to the config part, edit the config.php, put your site or subdomain link on a link and save it.
$config['base_url'] = 'http://example.com/';

Create database
You must make a database for your system. For doing this, enter the server and create the new database through MySQL® Database Wizard.
In the field of new database, enter the new name and click on next step,

In the new page enter the username and password and click on create user.

In the other page click on All PRIVILEGES and next step- your database will be created successfully.
Config database
You must enter the name of database, the password and the username in the field of application/config/database.php. For doing this, go to config part and edit the database.php file and enter your username, password and database-name and save it.

Upload the database
You must upload the database file. Enter the server and click on phpMyadmin.

In the new page on the left side upload the database file and click on import in the above.

In the opened page click on choose file and from install SQL, choose the main-file; then click on the GO.

You will get a message said your database is successfully installed.

Do you have any question?
Thank you for reading.