Firstly, because it uses the "count down to win something" mechanic that's primarily used by exploitative sites. People have to keep bidding in order to win, and loss aversion pushes them to pay more than they can intellectually justify for the product. If most sites that use the mechanic are evil, then the expectation is your site is no exception.
Secondly, the website looks really generic and based off a template. Like something that has been whipped up in a weekend to steal people's info. It would be trivial for somebody to create a scam version that's visually indistinguishable from your website. Having more content and a more polished appearance will help.
Thirdly, it's not clear what's in it for the operator of the site. If the products are given away then what's the catch? I understand you're giving away promotional items, but that's not enough to fix this first impression. You have to explain to people why the site exists. Is it a nonprofit? Are you getting paid? By who?
Finally, your explanation page makes no sense. Your target audience will never care about multiplexers. You've got to have at least a simple FAQ that answers questions like "Is this a scam?" "How does this site make money?" "Why is it free to enter?", and so on. A huge heading on the front page "Play for free to win promotional material. No catch." would probably help alleviate your visitor's concerns. But you'll have to do a lot more to make it seem less fishy.