From the Model Mayhem FAQ:

How does a Talent Recruiter Account Work?
Talent Recruiter accounts are designed for non-artists to hire approved Model Mayhem members. These accounts are automatically approved – meaning you can register an account and get started right away!

If you would like to hire someone from Model Mayhem, you must first post a Sponsored Casting to tell the members on Model Mayhem what you're casting for. This is by design and there is no other way to utilize a Talent Recruiter account.

You may find these articles helpful as you use Model Mayhem:
Recruit Talent on Model Mayhem with Sponsored Casting Calls
Getting the Most from Casting Calls