It is a simple five-step process:
1. Make sure your debit or credit card has an IC chip in it, European ATMs expect to encounter a chip and some behave badly when there is no chip.
2. Make sure your four-digit NUMERIC PIN works while in the US. Only four-digit PINs work in EU ATMs...
3. Make sure your bank or credit union knows what dates you will be in what country, so the card(s) will work there. If you fail to do this, fraud prevention computer programs prevent use in foreign countries. I notify about one week in advance of my planned departure.
I did this and was even able to make purchases on Amazon.es, for delivery in Spain, using my US Prime account. Of course, I had to set up a new delivery address. But, it only worked because the bank knew I was in Spain. I could not make the purchase on the Spanish site, from the US, for delivery in Spain.
4. Make sure you have enough funds on hand to cover your ATM withdrawals, factoring in the exchange rate, and any "convenience fees" you might be charged at the ATM. I have been charged a €3 fee for using my Visa Debit card in Spain. But, my credit union refunds these non-native ATM fees, up to four monthly.
5. Relax and enjoy your Camino...