As for receiving early education supplies for free, there must be his purpose, not to say that he will give them to you directly. If you leave your mobile phone number, they may call you, sell you products, and then say that if you buy their products, they will give them away for free. At some point, you may be tempted to buy their products, and they will also give you gifts-I guess that's what they mean by "getting preschool supplies for free". And children's products are generally very profitable, you have to earn, and you don't lose money by giving something.
I don't know if you are worried that the message they left you will have other uses. I think not.