[yith_wcaf_registration_form] shortcode shows the affilite form, so your users can submit their affiliate appliction from any page of your website.
You can customize the fields of the registration form YITH > Affiliates > General Options > Affiliate Registration as explained here.
If the affiliate has already applied for the affiliate programme, a message will be displayed to inform about the submitted application.
The available attributes are:
show_login_form: (yes/no) show or hide the login form together with the registration form
login_title: you can set here the title of the login form, if displayed
register_title: you can set here the title of the register form
[yith_wcaf_registration_form show_login_form="yes" login_title="Log in here" register_title="Apply for our Affiliate Programme"]