You can find there step by step manual how to download theme & plugin after purchase:
1) Login to your account
2) In your account, go to HISTORY AND DETAILS OF MY ORDERS
3) Click on order reference code
4) Scroll down and click on highlighted name of Theme
Now unzip downloaded file and upload theme and plugins separately.
You can get language to your osclass here: http://translate.osclass.org/projects/osclass