It's almost impossible to get it. It can only be acquired through trading or actual free robux games.

There is no way to get free Robux, those games that claim you will are a scam

You can only get it form some games like scam games that ask you to join the group but if they ask for the password dont type your password because it will give somebody the information and they will hack into your account and probably change your password and steal your robux if you had any robux