If I host Confluence Cloud on my own server, can users in the field access documents from the cloud using a tablet, mark them up using a stylus, and save the document back to the cloud?

[Milo Test]

First off, you can only host Confluence Server.

Second, regardless of the hosting, users can comment on attachments (if you've given them Comments permission), and they can download attachments and mark them up, and if you've given the users Attachments Add permission, they can add them back in.

[David M. Frazier]

I apologize for this misunderstanding.  So when Confluence Cloud is mentioned, that solution only refers to Atlassian hosting for you, correct?  Thank you very much for this answer.

[Milo Test]

Correct. Even if you host it via Google's, Microsoft Azure's, or Amazon's cloud, it's still Confluence Server.