PayPal Plus. Return URL?

In the rest API interface setup on PayPal it asks for an OAuth Return URL. What should I be entering into this field?

Thanks

PayPal uses this parameter if you plan to use "Login via PayPal", example our plugins SocialLogin. Set your store URL if you don't want to use "Login via PayPal".
But if you install plugin SocialLogin you you see this Return AOuth URL on plugin configure page.