how it is a scam if they are not requesting any money, but they are offering everything?
i can't see as a scam sincerely
It's probably more of a publicity stunt or attention seeking by the fantasist who created it than a traditional scam, but I think they might have charged people a fee to review their applications and they're selling merchandise etc but regardless of their motives one thing is for sure it's not going to happen as there's not the money or technology for it.
Well, we don't know that for sure as of now. It's what will happen over the span of the next 10 years that will dictate whether this mission will become a reality or a complete fail.
It will never happen, it will keep being delayed over and over again, it already was postponed, initial schedule was to get humans on Mars by 2023, IIRC.
It could be a way they can get more funds to fund their personal needs. I think this not a government project but i private company is the one responsible for this shenanigans and they have been asking for donations and asking participants to pay when they have passed some tests/interviews.