Credit cards are not widely accepted in Germany. Germans generally use cash or EC/Maesto debit cards, and you can't get an EC card if you're not an EU resident with an EU bank account (which can be hard for Americans, and, to a lesser extent, any foreigner, I'm sure).
I used to have a Maestro-branded debit card (in the US) when I was younger. I have no idea if it's the same system and/or if they're compatible. I checked my wallet and my current debit card has no Maestro branding.
I've more than once found myself halfway through a meal before realizing that I might not have a way to pay for it.
https://www.german-way.com/germanys-cash-culture-geld-stinkt...
