(Windows servers "always" run PHP as a CGI app, so this FAQ may not apply to Windows hosts.)
While Zen Cart is "best" run on a server running PHP as an apache "module", some hosts only run PHP as a CGI application. There are generally more restrictions and limitations in functionality if this is how your PHP hosting is setup.
A much requested feature in Zen Cart™ was the ability to have unique information layouts for different types of products.
For example a Music Video needs to have different information stored and displayed, compared to say a Garden Bench.
So, if your customer pays using the "offline credit card" module, you DO NOT have the payment ... all you have is the credit card number.
Using the offline credit card module, after you've processed the card manually in your credit card terminal and obtained an authorization number from the bank, then you need to ...