For Free products, you can use Infusionsoft opt-in form on your squeeze page and integrate it with DAP. Just set the action trigger upon opt-in (within Infusionsoft) to point to http://yoursite.com/dap/dap-infusionsoft-optin-productID.php
NOTE: Replace productID with the actual DAP product Id.
So if you want to integrate a DAP product with the DAP product ID = 10 with Infusionsoft, then ftp to your site, download /dap/dap-infusionsoft-optin.php, copy contents of /dap/dap-infusionsoft-optin.php to /dap/dap-infusionsoft-optin-10.php. Change $default_product_id to 10 in the dap-infusionsoft-optin-10.php script. Upload this script to the dap folder on your site (via FTP).
Set the web form action trigger within Infusionsoft to point to http://yoursite.com/dap/dap-infusionsoft-optin-10.php (replace yoursite.com with the name of your site). Also install the Infusionsoft SDK as described here –