Why can't each user log in to their individual marketplace dashboard?

Why isn't that working? Take a look here: http://marketplace.3dmakers.com/mattu/wp-admin/

Also, why don't the individual stores have any theme? Look here: http://marketplace.3dmakers.com/mattu/

Thank you for your help. Please send me an email at #REMOVED BY STAFF#. I'm the developer for this site. If you send the email to the default email address, I'll have a hard time receiving it.

Thanks again!