You made two different threads with the same question, and didn't even post in the release thread for the mod in question? Your question was posted about an hour ago, and since you didn't receive an answer within that time.. it's bad support? Really? No one is required to help you with modifications. vBulletin.com is all about the stock software, they will never support modifications.
https://vborg.vbsupport.ru/showthread.php?t=230543
Anyway, upload the contents of the "upload_this" folder to your forum root. Eg: /home/username/public_html/forums
Then login to the Admin CP, on the left-hand side look for "Plugins & Products", click to expand then click on "Product Manager". On the right-hand side, you should see a link for "[Add/Import Product]" - click on that link. Then, click on "Browse", find the "product-itrader.xml" file on your computer and then upload.