If you do not have SSO (single sign-on) set up in your environment and you want the user to be able to request an account, then you can set up the Request Account link to display on the Sign In screen.
When SSO is configured on the environment this link will not display.
Navigate to Admin Settings > System Config > General > User Sign In.
Check the Allow User Creation check box to display the Request Account link.
Uncheck the Allow User Creation check box to hide the Request Account link.