Your passport must not be more than 10 years old and must be valid during your entire stay. While the official requirement is that it's valid for the duration of your visit, it's strongly recommended to have at least 6 months of validity remaining.
You will probably be asked by the airline check-in agent to show proof that you have either a return ticket, or proof of transit to another country, or a valid work or Digital Nomad Visa. This is standard procedure—they're just making sure you have a plan to leave the island. US citizens, Canadians, and EU nationals don't need a visa and can stay up to 30 days without one. US citizens specifically can extend their stay up to 90 days, while some other nationalities can request extensions up to 180 days.
If your country requires a visa for Aruba, you'll need to apply in person at a Netherlands embassy or consulate before you travel. You can check the complete visa requirements list on the Dutch government's website. Keep in mind that even if you're visa-free, you still need to complete the ED Card—these are two separate requirements. The ED Card confirms you're approved to travel, while visa status determines how long you can stay.