from typing import Dict


def generate_userlist(users: Dict[str, str]) -> str:
    """Generate valid userlist.txt from the given dictionary of usernames:passwords.

    Args:
        users: a dictionary of usernames and passwords
    Returns:
        A multiline string, containing each pair of usernames and passwords in double quotes,
        separated by a space, one pair per line.
    """
    return "\n".join([f'"{username}" "{password}"' for username, password in users.items()])