It's using the V4 SDK.
If you're getting error #7 response from CURL, that means your server could not resolve the DNS name.
Thus, you probably need to talk to your hosting company about your server's CURL setup. GoDaddy isn't exactly the ideal host for running ecommerce systems, esp when external communications are necessary.
The module should recognize the CURL Proxy settings from your Zen Cart admin area (under Configuration->My Store).
What happens if you run the curltest.php script from your /extras folder? ie: www.your_site.com/extras/curltest.php?paypal=1