I'm not familiar with the details, but if you go to the mapillary website (and are logged in), you see in the right box, the rightmost tab 'projects'. I think thats exactly what you are looking for. How it works, you still have to figure out. It says: "Projects are private Mapillary repositories. You can switch to a project that you’re a member of in here."
edit: Private repositories Starting at $500 / month Source