When affiliates log into the affiliate portal area they can see their affiliate links, promotional codes like text ads and image banners in the Creatives menu. By default, Affiliates Manager plugin shows the home page URL as the default landing page URL.
Home page is the address that people type in their browsers to reach your WordPress site. WordPress saves this value in the general settings menu of your admin dashboard (Settings -> General -> Site Address).
You can customize this URL if you want to. Simply navigate to the Advanced Settings tab and enter your landing page URL in the Default Landing Page field (Affiliates -> Settings -> Advanced Settings).
Your affiliates will now see the customized landing page URL in the Creatives menu.
Make sure that the URL points to a page on the same WordPress install where the affiliates manager plugin is installed. If you point to a sub directory where another WordPress is installed your links will not get tracked.