Yes, things do change. A landing page does not have the code for sending the form, so any forms on the page may not send and/or may not be setup properly if the page is not marked as a capture page.
You can create optin forms using HTML form creator.
You can add custom fields and copy/paste the code to your 3rd party website.
Login to your SWREG
Get your Shop ID
from the top of the page.
Create a new product
(If you already have a product Just copy its id)Creating A Product
Get the API Key
Your API Password
can be anything you want it to be. Write it down so you have a copy.
Inside of your side go to Manage Billing
(/admin/billing.php) and select SWREG from the drop down. On the next page you will specify the amount and paste the values you copied from SWREG.