I presume that the following is the message you see.
"AcroForm" usually refers to the PDF form that is authored with Adobe Acrobat Pro/Standard and that is not a special type of static or dynamic XFA form authored with Adobe LiveCycle Designer.
You can fill out an AcroForm in Acrobat DC mobile products (for iOS and Android).
Instead of selecting "Fill & Sign" (which is a separate Adobe app), would you simply open the form and fill it out in Acrobat DC for iOS?
Do you see field highlighting in light blue like this?
thank you for the information. The problem I'm having now is the information I enter on the document is not being saved once I upload the document to Box. Is there something else I need to be doing?
I think that your forms data is saved and still there. But the PDF previewer that Box uses does not show forms data or comments. Apple iOS apps (e.g. Mail, Safari, iBooks) have the same problem (i.e. the lack of support for forms and comments).
Please download your PDF form from Box and open it in Acrobat DC for iOS or the desktop version of Reader. You will be able to view the forms data again.
Hope this helps.