Models can access the model login page by using the option highlighted below on the initial user sign in page.
Here, they can select the Signup option shown below to register themselves.
On the registration page, they can fill in all the necessary details, and upload any one of the accepted IDs before clicking on Register new account on the bottom of this page.
Note: Models will need to verify their email account and the admin needs to verify their documents and activate account before they can login.