Using DocumentCloud on SharePoint - Message to use Adobe Reader?

[Søren5E3B]

HI

We just started using the DocumentCloud integration to O365, but get this message when trying to edit PDFs based on a template:

This document contains some form fields that are not supported in the viewer. Please use Adobe Acrobat Reader to fill the form

We can edit and save, but I'm not sure what is causing this message?