You must have an Apple ID to download an app from the App Store. You can create an Apple ID with a credit card on file or not. If you are giving these credentials out, you may not want a credit card attached. Follow this alternative method: Create Apple ID without Credit Card
On a computer, go to https://appleid.apple.com and click Create an Apple ID.
Follow all steps on the site and make note of your email address and password used. This will be your Apple ID and password.
Before your Apple ID is active, an email will be sent to your email address asking to confirm your account. Confirm your account via the link on the email. You will need to enter your Apple ID credentials. Your Apple ID is now active.
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Alternative Method:
Create Apple ID without Credit Card
Following these steps will allow you to create an Apple ID without a Credit Card on your account. Any users that know your Apple ID will not be able to make purchases.
For this method, you will need to have iTunes installed on a computer. If you do not have it, Download and install here: http://www.apple.com/itunes/download/
After iTunes is installed, open iTunes. In the left-hand side menu, click iTunes store.
At the top of the iTunes window, click App Store.
Find a free app, any free app, and click on it. On the app’s information screen, click the Free button.
Make sure that there are no other Apple ID accounts signed in. Logout.
It will ask for your Apple ID and password to download. Click the“Create Apple ID” button.
Go through all the steps in iTunes to create your new Apple ID.
When you get to the part asking for your payment information, make sure the None button is selected under payment options.
Before your Apple ID is active, an email will be sent asking you to Verify your email address (below).
After you verify your email address via the Verify Now link on the email, your account will be active.