I bought a new Surface Pro 6. I tried logging in with my Microsoft credentials used for office 365 business premium. I am the Admin. Same login I use on MacBook pro. I get message Microsoft account not found. I then Call support line. the guy says I have to have a gmail or other type of Microsoft account in order to get into the surface. I asked why and he said if he told me he would be fired. I will be returning the surface pro 6 today to the Microsoft store. It appears they do not allow you to use your own domain for credentials.