To add a login component, you will need to use the S-tag: [[S3]]

This will automatically add the login component to the page. 
Note: You will want to ensure that the Pagebuilder page is set to Secure
, as the login process requires a secure connection to work properly.  Otherwise it may redirect to the default "home" login . 

To make a Pagebuilder page secure:
  1. Edit Attributes
  2. Go to Step 6: Page Properties
  3. Check box 1 "This is a secure Page that will be encrypted via SSL."
  4. Save and Finish