iPhone 17 Pro Max DIVA form assistance for immediate tax refund

Perhaps you'll find some useful information here:

https://sede.agenciatributaria.gob.es/Sede/en_gb/viajeros-trabajadores-desplazados-fronterizos/devoluciones-iva-compras-viajeros.html

Do NOT buy a phone in the US if you live in another country. The warranty will not be valid outside of the US.

As for taxes, no, the staff at the Apple Store can't help you with that. You're not going to get a tax refund from the store where you purchase it. That's not how things work in the US.

If you are buying in the US:

There is no Value-added tax, only State Sales tax (and in certain areas like New York City) Local Sales tax. These taxes are in addition to the quoted prices, and will be added at checkout. Rates vary, but are typically 5 to 9 percent.

State and local Sales taxes are NOT refundable. There is no DIVA form, and US sellers will not know what you are talking about.

If you buy a phone in the U.S. for use in another country,

• You won't have a warranty that is valid in that other country.
• You will get an iPhone that doesn't have a physical SIM tray.
• You won't get a refund of any sales taxes that U.S. State and local authorities require Apple to charge.
• You may have to pay import and customs taxes to the authorities in your own country, on top of the sales taxes that you had to pay because of U.S. State and local law.
• You might be in violation of U.S. export control policies, depending on where you take the phone.

In addition to Kilted Tim's excellent advice, I would add that, depending on the model and color phone you want, you may find you can't get one until sometime in October.