Like many countries around the world, Antigua is the latest to bring in a digital arrival form. These include Singapore, Malaysia, Barbados and more recently Thailand, along with the Maldives and Mauritius. These are essentially the old forms you used to do onboard the aircraft, ready for when you land and are relatively simple to complete and different from a visa.
The new Antigua form can only be done via a mobile phone (or mobile browser) at arriveantigua.com, and only within 72 hours of travel. They have made it easier by allowing to upload, along with flight details and where you are staying.