How can I sync one PDF across iPhone and Mac (including highlights/comments) while still using it locally offline?

I’m trying to figure out the best workflow for reading and annotating a single PDF across my iPhone and Mac using Adobe Acrobat.

What I want:

• One single PDF file (not separate local copies)

• Highlights and comments synced across devices

• Ability to open and read it locally (offline) without using data every time

• Sync annotations automatically when I’m back online

What I tried:

1. I uploaded the PDF to Adobe local storage on my iPhone.

2. Then I chose “Save to Adobe Cloud.”

However, when I tested it, the cloud version seems to be treated as a separate copy. Highlights made on the locally stored version do not sync to the cloud version. That confused me, because I chose “Save to Cloud” (not “Save a Copy” or “Send a Copy”), but it still behaves like a duplicate rather than a single synced file.

From what I understand:

• Files stored in Adobe Cloud sync annotations across devices.

• You can also make cloud files available offline in the iPhone app.

So my questions are:

1. What is the correct way to have one single PDF that:

   • Syncs highlights/comments across Mac and iPhone

   • Can still be accessed offline

   • Syncs changes once I’m back online

2. What is the difference between:

   • Storing a file in the iPhone “Files” app (including the Adobe folder), and

   • Storing a file directly in Adobe’s local storage inside the Acrobat app?

Both seem to be saved locally on the iPhone, so why do they behave differently in terms of syncing?