I don’t know much about this specific company/website, but I looked at them just now and to be honest, it’s not sitting well with me. For starters, I couldn’t even figure out what the whole “business model” was based on. And that’s usually the case with Ponzi or pyramid schemes. I suspect its something along the lines of a pyramid scheme where you make money by bringing in other paid members, but I am not sure.
Now, unfortunately, there are a lot of scams when it comes to GPT sites. So it’s best to stick with well known, trusted sites that have been around for a while. You don’t want to complete offers for a month then when it’s time to cash out your earning find out that the site no longer exist. Trust me, I have seen a lot of “here today, gone tomorrow” rewards sites.