no credit card to put on file

Use iTunes Gift card where you can buy in many places.

Read here: Redeem and use iTunes Gift Cards and content codes - Apple Support

While not signed in, try to download a free app, you will be prompted to create an apple ID. One of the options will be use none (no credit card). If you've already created an apple ID with your email address, you'll need to use a different email address.

See Create an iTunes Store, App Store, or iBooks Store account without a credit card or other payment method for more info.