Money in Croatia

If they have requested payment in Euros, that is what you should do.

Croatia begins officially using the euro in January 2023. Although it’s common for sobe owners to request payment in euros ( most visitors are Europeans who have euros in their wallets), because the kuna is currently the legal tender in Croatia, businesses have to accept it for payment as it is still the coin of the realm.
I think I would simply let the owner know that since you’re coming from the US, you will not have any euros with you to pay them with. They should be fine with that.
Be sure to use a mainline bank ATM to get Kunas as there are some commercial companies that put highly visible ATM’s on the tourist trail and they charge exhorbitant fees and use predatory exchange rates. Pivredna Banka (PBZ), Raiffeisenbank Austria Zagreb (RBA) and Splitska Banka are three of the largest mainline banks in Croatia.
Have fun in Croatia!

We never used the Kuna we had except at the farmers market. Euro was the main currency - well except when we charged things like our hotel room it was in Kuna as we selected the local currency. Good to know they will move t the Euro in January.

I am in Croatia right now. I have been here for 8 days. Everything I pay for has been in Kuna. A few places would also accept Euros. My apartment I am in right now quoted in Euros and wanted cash. I pointed out that I was already in Croatia and did not have access to Euros from a bank machine. She of course accepted Kuna.

We just returned from Croatia two days ago. I had gotten some Kuna from my bank here in the US before we left, and then got additional Kuna at ATMs in Croatia when needed. Definitely use ATMs at a bank like OTP (not random ones in tourist areas). Also, i recommend always choosing the option to "decline conversion" to avoid weird rates and charges (Rick Steves has recommendations on this too). You definitely need Kuna - almost everyone wants cash rather than credit cards, and we never used Euros there (although I'd say that if someone has specifically requested Euros, I'd honor that. If you have time, you could get the Euros from your bank ahead of time). Have a great trip!

You may want to avoid the ATMs in Croatia - a "good" fee is "only" 8% - we got stung for 11% at a bus station! Its a complete rip off and I am yet to find ATM that doesn't charge a huge amount. We have resorted to changing Euros and US$ that we had with us. There are plenty of Exchange offices all over and they will give you a good rate - close to the interbank rate.

Plent of places don't take cards - even quite fancy restaurants in tourist places like Split. We now always ask before looking at the menu.

If you don't have Euros as others have said use Koruna .

Every shop has to display all prices in euros and koruna - but that dosnt mean they will take euros most/all won't

If you don't have Euros as others have said use Koruna.

Use Kuna, the Koruna is the Czech currency.