NixOS AWS can't log in after creation

Hey guys,
I am trying to use nixos in aws with the ami ami-07df5833f04703a2a for an university project, I use the default ssh key so there shouldn’t be a problem with that, however if i try to connect via the web interface with the user root, it writes Error establishing SSH connection to your instance. Try again later.
Is this the correct user for this image or does this image use another user and what is the password of the default user?