Trying to install El Capitan

To find out what the issue is, you need to contact Apple support directly.

iTunes refunds, billing issues, or start with the Contact Us link at the bottom of this page.

https://www.apple.com/emea/support/itunes/contact.html

I have tried multiple cards w/ money on them, and none of them work.

If these are prepaid debit cards that you purchased in a local store, you are not offering a valid payment method. Apple does not accept prepaid debit cards.

Aside from using the None option or redeeming a local iTunes Gift card, the only valid payment method is a credit card issued by a bank in your country of legal residence, with a verifiable billing address for the account, in that same country.

Late 2012 Mac mini, macOS ?;  Watch, 38 mm silver AL, Watch OS 2.2.2; iPad Air 2 & iPhone 6+, iOS ?;  Apple Airport Express

Bad idea to create another Apple ID. Multiple Apple IDs just make a mess of things.

The None option doesn't always show up in everyone's account. You need to buy & redeem an iTunes gift card or supply a bank issued credit card.