I had the chance to have in my hands an old mac mini from 2009. I turned it on, it works perfectly. Currently it runs Mac OS X 10.6.8.
Now, I would like to try to upgrade it to a slightly newer version, like El Capitan.
So, I created a brand new AppleID on https://appleid.apple.com with all my data, including a valid credit card. I checked and Apple did registered and then deleted a transaction with a small amount, to check the credit card. I also confirmed my email using the code Apple sent me during the AppleID registration phase.
After that I opened the "App Store" app on this old Mac, I navigated to the page where I can download El Capitan from, and a pop up asks me to input my AppleID credentials.
I've done it and a pop up tells me that my AppleID have not yet been used in the app store and that I have to verify it.
I click on "verify" and a second pop up tells me I have to update the software and the OS to be able to verify my AppleID.
So I'm now stuck in this catch 22 situation.
Can someone explain me if there's a way to solve it?