Ebook not found in Digital Editions App on Macbook. (It does appear on ADE on iPad.) How to sync?

[YK05092023]

I installed Adobe Digital Editions on my iPad Pro (iPad OS 16.4.1). Then, I installed ADE on my Macbook Air (M1, MacOS 13.1). On my Macbook ADE, I cannot find the Ebook that I have on my iPad ADE. How can I synch them? I was instructed to try the following steps to synch my two devices. But, my issue is that my Ebook only appears on my iPad ADE. 

1. On your Macbook, open ADE and right click on the book in question. Select "Show In Finder," and take note of the location, or keep the window open.
2. Connect your iOS device to iTunes.
3. Once in iTunes, go to your connected iOS device (from step 2) and select "File Sharing," which should be on the left side of the window.
4. Scroll to and select ADE (assuming that you have it downloaded to your iOS device).
5. Either select "add" or drag the file into the window and sync the device.
6. Your book in question should automatically show up on your iOS device.

[YK05092023]

One day later, my ebook showed up on my Macbook ADE. But, my Macbook ADE and iPad ADE are still not syncing. I tried to follow the steps given above but realized that iTunes is no longer available. Can anyone teach me how to sync contents in the ADEs on Macbook and iPad without using iTunes?