Create a ‘Registration Form’ for the new customers. You need to configure the following details: 
Registration Form: Select the ‘form’ for the registration from the list of forms.
– Note: These forms are related to the contact module.
Title: Insert the label to display the title of the Registration form.
Register Button Text: Insert the button label for submission of the registration form.
Redirect To: Select the page where you want to redirect the user when they successfully registers.
Enable reCAPTCHA: Enable the reCAPTCHA option to the customer portal Registration page to protect from spam. The portal users will get the reCAPTCHA V2 or V3 as you have configured in the “Portal General Settings” from the Settings → Portal Settings. 
Design Layout: You will get the 3- predefined Design Layout (Style) for the Registration page. By clicking on any design, you can preview the layout. Select any design layout to display in the customer portal.
After configuring the Registration widget, click on the Save button.