At the moment it's possible to connect a profile in Edge Preview only to a MS account (@outlook.com and similar). The multiple profiles feature coming with Edge Preview would be way more useful if we could connect one of the additional profiles to a work/school account such as those provided with an Office365 subscription, so to manage different sync bookmarks and data.
@Zenith601 completely agree. The "Sign in with your work or school account" feature has been listed in the Coming Soon section of the welcome page ever since this program launched. Hope they add it soon.