Most files on Acrobat for iPad do not go to next fillable field when you hit “tab” key on Magic Keyboard. The only option is to select next on the bottom left of iPad screen. I have compared dozens of of files on my Mac, and the tab on a computer works as expected designed. I even checked the fields in the Prepare Form tool and they all have the same form and function, and should therefore work the same on the iPad. The app knows to offer you the “next” or “previous” options at the bottom of the screen while filling the form, but it doesn’t recognize the “tab” key itself.

You also can’t use the Curser that appears on the iPad screen with the Magic Keyboard trackpad to “click” into a field. You have to tap the screen. Similar issues I think.