Why can't I open an outlook.com account on Mail (mac Mini)?

I have an .outlook.com mail address, which works in Mail on my iPhone and iPad, but not on my Mac Mini. Whenever I try to add the account I get the (usual) message "unable to verify account name or password". (I say "usual" because I get this message very often when I try to sign in to a Microsoft product, even after I have gone through the rigmarole of changing the password. I wonder if anyone else has had this experience with Microsoft sign-ins.)