Can I download a free app from the App Store without a credit card?
To get an app for free (if you didn't get the choice to pick None as payment option) you should open your installed ITunes program. Then from within the program go to ITunes Store and pick any free app and try to buy it (Google Translate or some other one). It will tell you to login/register into ITunes. If you create account from there you will have a choice to pick None as payment option.

This worked for me several times for my customers.